I'm reviewing this as someone who hasn't read the novel or watched the animation. I discovered this show because Netflix recommended it to me. I didn't know any of the actors, and while I do like video games, I first gave it a skip for a long time because of other shows. But then I eventually decided to watch it and I was not disappointed. All the things I thought would be in it and would irritate me, failed to happen. It was fantastic.
To keep to the point:

PROS:
No drawn out excess filler in the episodes
Great characters (male and female)
Great character development
Great character relationships
Great acting
No romance (thank goodness, because it generally makes the characters behave like idiots and doesn't contribute to the plot)
Not too predictable at all
Exciting
Good feels
Humorous
Some suspense
Great OST
Great pace
Great action/CGI fight scenes for the in-game play
Clean, attractive sets
Great casting all around

CONS:
'Happy' is a really lame name for any sports team (but it's hardly a dealbreaker and doesn't change how great the show is)

I'd recc this for anyone who likes video games and also good shows that represent a good balance of fun/humor/drama/plot with consistent acting, and I'd probably watch it again sometime. Looking forward to a season 2, I hope they stick to this formula though, or it'll lose it's great vibes.