I think this must have been one of the best mangas I've read in a long, long time. The art is beautiful, although not amazing, but it is the story that really captures you. From beginning to end, everything flows together, everything makes sense, and everything is sweet, sad, touching, tragic and wonderful. You find yourself thinking back on early scenes, going "Oh.. so that's why!" and "Now I understand this better."
Keidai is a bit of a spaz, but he gets better, and he's never so dumb he's annoying. In fact, if he didn't have the personality he does, he'd be a bit of a Mary Sue xD And after a while, you begin to know the characters so well you can think like them. NG Life had all the cliches - the evil school teacher, the best childhood friend, the love rival, the love rival for the other person - and it took all of them and turned each character into someone you'd love, root for and enjoy reading about. For a manga where every character has two different names, it was remarkably easy to keep the cast straight.
And that's not even to mention all the ROFL moments scattered liberally around. The mangaka has a great sense of humour to add to her amazing storytelling skills. Plus the aww/kiss scenes were so awwww, you can't help but reread them a few times, just to get your bandwidth's worth.
To sum it up, it was amazing. Read it. I think I might have cried. It certainly took me all the way from laughter to happiness to tears.