...but PLEASE, if you're going to grow out your hair into a shaggy style, DON'T make it into an 'emo-my fringe is stuck to my forehead' look...it's just annoying and unattractive...xD -Zac Efron for example...so gay and utterly unattractive... haha
Looking "good" in long hair, on a guy, is in the eye of the beholder. I think you would look good with long hair, but I'm fine with guys with long hair. 99% of my girlfriends would say you wouldn't look good with long hair because they don't like guys with long hair. And you're going to get different responses with long hair: depending on your clothing style, people are going to assume certain things about you. When a guy has long hair I would say there's a 30% chance he's a metal-loving video-game-playing nerd, a 50% chance he's a stoner, a 10% chance he's a surfer, a 35% chance he's an arty, sensitive hippie type, and a 90% chance that he doesn't have an office job (i.e. a well-paying job). Pretty frequently he doesn't care about current trends or what other people think. I'm not saying there's anything wrong with any of that! We're not in the 70s anymore unfortunately.