TL;DR - pros/cons
+ Amazing production values
+ Huge cast of diverse characters
+ Interesting main cast (for the most part)
+ Well set-up world
+ Diversity in powers gives space for huge opportunities
+ A whole lot of space to expand (other Kingdoms, worlds etc.)
- Very badly executed story
- Ending is terrible
- Main villain is neither interesting nor intimidating
- Fuckton of asspulls
- Most of the side characters are pointless and go nowhere
- Very little is know about majority of main cast
- More than a few dull moments before the final arc
Story in NnT follows Princess Elizabeth on her quest to reunite Seven Deadly Sins, Kingdom's strongest Holy Knights who are believed to have betrayed the Kingdom ten years ago. Initial setup works well, as it presents clear goal and a path of adventure. Its initial characters spark up the charm, and the mystery behind each of the Seven keeps you going. Unfortunately, somewhere along the line, it turns into a ... mess. You know, that generic plotline of "dude wishes for power so he combines with gods or whatever". That can work if executed well, but here, however, it was executed quite poorly. Story suffers massively from its own incapability to cope with its rules within universe, and relies upon random asspulls to salvage the concurrent plot. The vision is there, and is clearly present at the start, yet it is lost somewhere along the way.
I'll explain my first sentence in a little bit of a detail here, as the story suffers the most from it (possible minor spoilers ahead, so read at your own risk): the author seemed to think that by making it shounen, he couldn't pull out actual heartbreaking moments and instead gives us unsatisfying endings all over the place, overdrawn subplots that end abruptly, and a whole fuckton of asspulls, especially towards the end. If you want an example, think of a climax of Berserk's Golden Age Arc, but instead of playing out as it did, imagine if nobody died - that's NnT in a nutshell. Forming deep bonds that are tempered by death is nigh impossible here because you know no one within the main cast will die.
Another bad point of the story is the final arc - which in itself drew my initial score of the anime from 7 to 6. It's absurd on so many levels I don't know where to being. As I previously said, aside from the generic villain plotline, a bunch of new random shit is introduced out of nowhere without any prior mention, and even things that were mentioned previously were mentioned maybe 1 episode before that very thing miraculously spawned within the world. Ultimately, what this anime turns into towards the end is literally asspull galore, as a bunch of new and random powers and connections are introduced out of nowhere, numbing down my enjoyment greatly. I can't go into detail because I don't want to spoil it, but it gets cringe-worthy by the last episode, and that's not a feeling your story should invoke.
Ultimately, though, I stand by my initial statement: that the anime was ruined simply because of the demographic it was aimed at. It would have served it far better if it held deep and mature story with realistic stakes, fleshed out rules of the world, removing its pointless asspulls completely. I feel that most of the things that were actually resolved via asspulls could have been handled so much better, and that's only using things that were already present in the story.
On the other hand, anime looks and sounds gorgeous. It's colorful and there's rarely a dull moment in colors. Action varies from good to amazing, and there's enough diversity within the powers of Holy Knights to always showcase something new and amazing. Movements feel fluid and natural, and I was particularly impressed by fist fights in this anime, as they really were able to get my adrenaline going. The designs of the characters, creatures as well as the world are exceptional. They're varied enough for you not to get bored, but you'll still find yourself finding similarities between them. The whole anime is colorful and it never really dulls its own color pallet for the sake of "artistry", and that's something I appreciate.
It's been awhile since I've heard some good soundtrack in anime - surprisingly. The score of NnT is amazing, and definitely one of the high points of the whole thing. Openings and endings were done well, especially the first one, and the whole ambiance within each different zone really captures the feel. When it comes to voice acting, it can be a hit or miss, but for the most part it holds itself up. Another impressive feat here is the array of special effects for each special and not-so-special attack, as they really do vary it up. Sadly, production really is the peak of this anime, so props to A-1 on this one.
With the huge cast of characters that NnT boasts, it's obvious there's going to be good ones, bad ones and ... well, ugly ones. Elizabeth is your everyday cookie-cutter sheltered princess who goes on a journey and develops "strength" to fight for her friends. She seems more like a fodder than an actual character, as very little is actually done with her. In a nutshell, she's your lovely airhead princess with big boobs.
Out of the Seven Deadly Sins (well, Six), I actually enjoyed majority of them - some more than others, Ban probably being the highlight. Unfortunately, aside from Ban, King, Diane and, to a very small extent, Mel, we know very little of who the hell are these people. This is what holds the characters back immensely and it's mainly because the anime focuses far too much on its generic villain subplot and overall theme of "Holy Knights are actually evil, kyaaaah!" rather than developing its characters properly. My least favorite of Six is probably Mel, followed closely by Diane. Although Mel really is a badass character when it comes to fighting, he's your masked shounen lead. Sure, he has his moments, but there were far too many times I've wanted to punch him in the head for those moments to overshadow it.
Aside from them, there's, as I said, a whole fuckton of side characters, most of which you really don't care for. Quite a large number of them are used mainly as drama fodder and plot devices, so you shouldn't really get your hopes up.
Villain of the series is bad - not as he's bad in the sense of evil, he's just boring. Up until the very end, you have no idea what his motives are - yeah, there are hints "the start of the Holy War, release this, I gotta drink it to match them etc.", but they're just boring excuses. He's not charming, he's not interesting, he's even dull looking, and, quite frankly, he's not even badass as the ultimate enemy. His mega move is making some purple shit snow and then gathering it in one spot for like 30 seconds while everyone else around him sits and drools in awe. Good job ye Holy Knights.
I'd lie if I said I didn't enjoy Nanatsu no Taizai. However, I'd also lie if I said I was never bothered by its lackluster story and overabundance of pointless characters that go nowhere. If you exclude last 3-4 episodes, this show would definitely get 7, even bordering 8, however its ending is really, really good example of why you need to have an idea of your ending before you write it, because you can't use asspulls to save your story over and over again.
It's a fun watch, and if you're not a nitpicker like me, you'll probably get far more out of NnT than I did - and even I got plenty.
