I didn't think I was gonna be a fan of Nanatsu when I watched the first episode, cus the art was a bit not my style and the fanservice seemed to be in your face and obnoxious. Then I watched the 2nd episode for kicks. Then the third. Then the fourth. You get the idea. Soon I was obsessed.
Story: 10
Story was, as MAL describes it, outstanding. It didn't really seem all that stereotypical at first (though I saw Meliodas being a sin coming from a mile away... thought he was gonna be lust though lol) and as the plot developed, I found myself waiting for the next episode with bated breath. The way it captures you with each episode is unique and can only be credited back to excellent writing and a LOT of developmental work. So much love and care is put into each episode and that's what makes it worth watching, if not anything else.
Art: 8
The art, like I said, did not capture me at first. Too cutesy and the anatomy was ridiculous (what skinny female has boobs that big???????), but it most certainly grew on me. It suits the show really well and the background art was so amazingly detailed and beautiful. Though A-1 Pictures is generally known for the abominations of Aldnoah 2, Magi, and SAO, they honestly transferred manga-to-anime art so smoothly that I didn't even know it was A-1 until I looked on MAL. The animation is stunning, but A-1 has always been pretty good with animation so that wasn't too shocking. What brought this rating down was the amount of effort I put in before I liked the art. What saved it was its evolution and the gradual look of aging and maturity you can see in the characters.
Sound: 10
I could listen to the NnT OST all day. The openings and endings are so great that I can't pick a favorite, and the BGM suits each scene really well. Not really much to say here, good job A-1.
Character: 9
A-1 is known for its plot-annihilating adaptions. It loves to reduce characters down to their stereotypes and rip up plots like a dog rips up newspaper. I haven't read the manga of NnT, but the characters and plot were very well put together in my opinion. A manga reader may say otherwise, but this is just my own input. The characters develop so well and the backstories are tragic yet beautiful. One complaint I have is the obsession with Elaine, a minor character who was only there to advance Ban's character, and yet she continues to be brought back again and again and treated like an actual major character. This show's inability to separate protagonists from tritagonists brought its rating down.
Enjoyment: 9
If the fanservice was less boobs-and-ass-in-your-face-all-the-time, it'd have gotten a 10 from me. I guess that's just my own take on it, as I'm pretty sick of fanservice, so take that in stride. Still, its ability to smoothly transition from comedy to angst to action to ecchi was spectacular, and I stopped minding the fanservice after a few episodes. It really made me interested in the manga, and I have no regrets watching this series. It made my week so interesting, thinking about each episode for days afterwards. Nanatsu no Taizai is memorable, to say the very least. It has a sort of charm to it that makes it unusual for its type, and I recommend it to anyone who wants an excellent plot, a few good tear-jerking moments, and cute and powerful girls.