I look for games that use the iDevice to deliver a gaming experience that can't be done better elsewhere. I have a 360 and a PC, and both of those are suited better for this kind of game, and i'd rather play GTA:SA than a knock-off elsewhere.
I got it when it was .99 cents and I think it is worth it the missions start out lame doing the same thing ice this person cap this person, but when you get past the first mission set they get better, you just have to give it time. Also when I am bored I like to play just like I would GTA steal a car and just have fun driving around. I would say it looks a lot like GTA: VC