Went from G2X ( amazing phone btw ) to iPhone 4s now back to Galaxy s3 and I'm more than happy. Hardware wise it beats iPhone by leaps and bounds, zero restrictions it feels like. Software wise also you have amazing choices when it comes to sharing between apps and interacting with the hardware. My biggest gripe, which i'm sure extends from the development tools that are given is unification between apps. You have apps that are poorly coded and designed as if it belongs on the original gameboy and then you have beautiful apps such as USA Today, Spotify, Pintrest etc. Graphics wise things are kind of awkward. But man I'm more than happy that I switched.
Phone : T-Mobile Galaxy S3
ROM: Liquid Smooth 2.9