It's pretty much the same thing only that C3 is a much nicer looking experience +- some awesome UI stuff.
If you intend to finish a major project that relies on stability focus on C2, if you want to have a nice time while learning and experimenting for a few months until they fix stability then do C3.
Either way you learn the programming aspect.
Thanks for the response, I already got C2 with a template to start with; I was concern with the upcoming upgrade and how that would effect the game, I plan on making a series out of it.