I have this game for ps3 and I personally wouldn't recommend buying it. Over the years we've seen Sonic the Hedgehog gradually become incredibly different, and it feels like Sega is trying to stretch him out further. For kids around 12 then yes it may keep them well entertained but if you intend to buy this for you child then please take note:
The game doesn't run so smoothly on an old 50 Hz Television, you will find sequences incredibly choppy unless you have a 60hz framerate TV or a HD TV.

The loading time is awful, sometimes lasting around 20 seconds maximum every time you go to a stage.

Since the port from the Xbox 360 there are still glitches in the game which can sometimes be tedious and frustrating.

So if you choose to buy this make sure you have a decent television but if your eager to try it I would just recommend renting it.