When I read "You will gain weight" I stopped thinking about it. But if you want to put on muscle, sounds like it can help:

http://www.menshealth.com/nutrition/creatine-side-effects-what-it-what-it-does

I guess this one says you won't gain weight if you aren't eating at surplus (except for that few lbs of water weight):

http://www.abcbodybuilding.com/creatine myths and_facts.htm

Maybe somebody has first hand experience

What creatine does is it "creates" a larger energy reserve stored within the muscles, so that it will give you a few extra reps if you're lucky. But mostly creatine is used for it's ability to get water to be stored in the muscles so they look bigger.

If you decide you'll ever want to try it then be careful. It can go well, but you can also become very ill from it. It's all about how your body reacts to it. I've taken it, become almost deathly ill from it, and know people who take it without problems. I will never ever use it again. And also, when it comes to that "extra energy" I've never felt it myself, don't know how much extra it really is.