It's a great SDK for making cross-platform 2d games. (For cross-platform 3d games, Unity is currently the most popular choice.) You are sacrificing control of the technology by using it, or similar products, but that's only relevant if the underlying technology is more important to you than the game itself.
If the technology is important, you're probably better of creating your own engine (this will take a long time), or licensing an existing engine (i.e., the Unreal Engine) and modding it as necessary.
Thanks for the reply. I'm not fixated about the cross-platform functionality of any game I develop yet, because I am sure I will need to iterate through the design process a few times (and it might be easier to start over once I better conceptualize my idea).
