Story
Gekkan Shoujo Nozaki-kun does a great job adapting its manga counterpart to the small screen. The manga is written in 4-koma style, which can cause the storyline to become choppy and confusing at times. The anime really brings all of the smaller scenarios together to create one fluid story.
[ Nozaki-kun adapts content from chapter 1 to chapter 31 of the manga; the two stories are identical up to chapter 13 (where you will find small tidbits and/or explanations not present in the anime). From this point forward, you will find new stories (e.g. chapter 21 featuring Ken-san's background) as well as content seen in the anime, but in a different order. These differences are negligible and do not detract from the overall story. ]
Art & Sound
The art and sound are great and stay consistent throughout the series. The opening intro is upbeat, catchy, and full of color. (Definitely a favorite of mine!) The closing credits were lackluster in comparison.
Character
Although the characters could be described by many tropes prevalent in anime, each and every one one was extremely like-able. You can almost see the punchlines coming, but the execution is so well done, you'll still be left in laughter.
Enjoyment
I enjoyed the series so much, I ended up watching it twice: once alone and twice when I had company over. After previewing the first two episodes, each one of my friends continued watching until the end.
Overall
Gekkan Shoujo Nozaki-kun was definitely a hit for the summer 2014 season. I watched it on a whim thinking I was getting myself into another typical shoujo romance (and boy was I wrong). It started as something to pass time, but shortly became one of the series I had to watch as soon as the simulcast became available. If there's any series you should watch when you've got nothing in your queue, pick Nozaki-kun and you won't regret it.