There are mainly only two sides to the debate on this show -- those that absolutely love it, and those that strongly dislike it. Is there an abundance of melodrama? Yes. Does this show try too hard at some points? Sure it does. Does that mean that this show is bad? Not necessarily. This show is neither the best thing ever, as some people seem to be saying, but it's not the worst either. Basically, what I'm about to do is help find some middle ground between the two viewpoints.
tl;dr at the bottom for those that don't want to read a wall of text, but I still strongly encourage you to do so.
Story - 4/10
Kousei Arima was a prodigy at playing the piano. He dominated every competition on a regular basis by playing the music perfectly as it was intended by the composer. He was so dominant to the point where he became famous among child and adult musicians alike. However, after the death of his mother (who was also his instructor), he was unable to cope with it and eventually lost the ability to hear the piano. He then quit shortly after. For the next couple of years, the world around him became dull and lifeless aside from a couple of his friends, until he met this extremely cheerful violinist, Kaori Miyazono. She revealed to him a side and style of music he never knew existed, and eventually convinced him to give the piano another shot.
The premise doesn't sound too bad. In fact, the way it handles the romance plot is pretty unique. It isn't just simply your typical boy meets girl and then they eventually confess, blah blah; there's a lot more to it than that. It focuses more on Kousei's development as a result of Kaori's carefree happy-go-lucky personality. The story is told primarily in Kousei's point of view, and likewise the plot revolves somewhat around him. Other characters do get screen time as well, though, and occasionally we do hear their take on things too.
A big thing that really makes the story stand out (in the first half, particularly) is how it portrays the music. Why do we play music? Who are you playing for? What message are you trying to convey? Music isn't just there to pleasure your ears, it's used as a tool to speak from the heart. Who you are as a person, what you've gone through, and what you strive for are all expressed in how you play music. The notes may be the same, but the feel of the song can vastly vary with the way people play it. In other words, you take the music and make it your own. In doing that, you can really make the music have an impact on the audience. This kind of message opened up a new side of classical music (and just music in general) that I really didn't think about initially, and I don't mean that in a half-assed way.
So with all these positives in place, you may be wondering how in the world could I only give this section a 4. Well, just as there was a lot of good, there was a lot of flaws, particularly in the execution of the plot.
Melodrama. It's alright to have it in moderation, but in this show, it was taken to a whole other level. Almost every episode contains at least one overreaction to an event, almost to the point where it became hard to really feel the feels you were supposed to in the particular scene. Now, there were some instances where this was properly used and was actually beneficial to the plot, but more often than not, I found myself cringing and unable to relate to the character(s) at all.
Pacing. The pacing of this show was all over the place, but generally speaking, it was so slow to the point where it felt like it was beating a dead horse. Literally, I could look up the word "monologuing" in the dictionary and find the cover art of YLIA. Episode after episode, there was an absurd amount of redundant repetition, almost to the point where it became laughable. To be fair, the show did attempt to at least bring up a couple of little side plots every now and then, but in the end, they were mostly pointless and had no connection to the overarching plot.
Lastly, there's the comedy. Quality of comedy in general is unquestionably subjective, but personally, I found a good deal of it funny. My gripe with it is that it was terribly misplaced. You're in the middle of this deep, sad scene, and then all of a sudden you're slapped in the face with comedic relief that doesn't fit the scene at all. To put it bluntly, it kills the mood.
The story had a LOT of potential. I, like many others, was hooked at the beginning, but found it harder to watch as the show goes on. It really makes me wish that this was a 12 episode anime instead.
Art/Animation - 8/10
The art in this show fits the feel of it really well. The characters designs are rather unique; they each all have full lips rather than a simple line like you see in almost every anime nowadays, and it's little subtleties like this that adds a sense of realism to the show. The brightness of the setting also appropriately fits each situation. It's colorful and bright when things are more lively, dark and dull when things are more depressing, you get the idea. The actual art itself is very good-looking too. Animation was pretty solid and up to par with today's standards, but occasionally it can be less than stellar.
Sound - 9/10
Now, I'm not a fan of classical music at all. I don't necessarily hate it, it's just not my bread and butter, but I've started to open up to it a lot more than I originally was. The BGM is nice and really adds to the emotions that the specific scene is trying to convey. The solo performances are especially good for reasons already explained. I'm also a personal fan of the OPs and EDs, both of which suit the show well. Not much else to say here, really. It's just solid.
Character - 6/10
As a romance and drama, the characters really are the backbone of the entire show. With the slower pacing, the characters get added depth, which is critical for a show like this to do. I must say, it did a damn good job in that aspect. Many characters had their own backstory (although a lot of them did start out bland), and there aren't many one-dimensional characters that get major screen time. Most importantly, they're all likable in their own way.
Something I felt was important is the development of Kousei. Being the main character and all, he's pretty much got to be the best developed character of the show. Thankfully, he is. He starts out as this mopey, depressing, and generally dull kid, but gradually develops into something much more. After losing his mother, he really had no reason to play music. All he ever knew was to play it perfectly as the composer intended, and for the purpose of pleasing his mom. Enter Kaori. Her unique style of playing opened up Kousei's eyes in a big way, and inspired him to take up music again. His journey together with Kaori and friends has been helping him break out of his shell, and his development bit by bit was superb.
Again, with so much good, why give it such a mediocre score? Hear me out.
I touched upon this earlier, but many of the side characters were pointless. Their development overall pretty much served no purpose. Instead of adding to the story, their screen time swayed away from the main plotline, which is not how it's supposed to work. Yes, it's cool to hear someone else's story every now and then, but not when it distracts the audience from what's really important.
Another thing -- Kaori. This is kind of tied into the pacing, which I also touched upon earlier. She never really received significant development until the very end of the show. Up until that point, she's nothing but a mere plot device used to stir up drama. For the duration of 21 episodes, she was just a cute girl that's meant to be likable and appeal to the audience, but with no depth whatsoever. It would have helped substantially to show her insight on the status quo as the show went on.
Enjoyment - 7/10
With all that's been said, I enjoyed this anime. It had it's ups, it's definitely had it's downs, but even with all that went wrong, I thoroughly enjoyed it. I felt a strong connection with Arima and Kaori's relationship, which at the end of the day, is what's most important for this show to do. In the last several episodes especially, feels were definitely felt. Unfortunately, personal enjoyment is not a direct indicative of how good a show is.
Overall - 6/10
In my opinion, this anime doesn't deserve to be rated as high as it is. Again, I'll repeat: I did NOT think this anime was bad at all. In my book, a 6 is right around average. But to be rated #13 overall at the time this review was written? It's pretty undeserving with all the glaring issues that are present throughout.
I'll try to sum it up as simply as I can: for more intellectual viewers, stay clear. The mannerisms and actions that some characters take in this show can be mind-boggling and potentially frustrating at times, and the plot is painfully stretched out. For more casual viewers just looking to rack up the feels, this is definitely worth a look. If there's one thing this anime excels at, it's just that.
+Unique style of romance
+Opened up my eyes when it comes to classical music
+Pretty funny comedy every now and then
−Comedy is terribly misplaced
−Pacing was all over the place, but generally speaking, it was way too slow
−Monologuing to the point of beating a dead horse
+Background/scenery is really nice
+Art fits the mood well
+/−The animation is average, up to par with today's standards. Not sure whether to put this as a negative or a plus lol
+BGM is solid, adds to the scene
+OPs and EDs are nice
+Solo performances are very good, further explained in the review
+Great development of Kousei
+Audience can sympathize with emotions of each character
+They're all likable, the show does a good job of getting the audience attached to them
−Side characters were insignificant to the overall plot, distracted audience from overarching plot
−Kaori's development came way too late, she was mostly a plot device the whole time
+Even with all that went wrong, it was very enjoyable overall. Ending was very well-done, and feels were definitely felt
−Unfortunately, enjoyable =/= objectively good