Support may be fading a bit as 6677 said, however i think it's still a good framework to learn. I learned SFML at first and then moved to python and pygame then to XNA. I didn't completly understand SFML at first, then pygame was easier to understand, now XNA I'm finally understanding the process in which a game is "put together" if you will. < Probably sounds like a n00b statement but it's true.

What I say here is not a fact, but an opinion, please don't start war.

Personally I believe C++ is faster than pretty much any other choice you have. However developing anything with C++ will take more time to get it working and even more time to get it right. Performance provided by C++ is useful only if you are going to develop (very) heavy game (application) and bother to do optimizations. I've had a lot of troubles with Java, Flash, Unity (but not C#) in the past, I have them even right after fresh Windows install, therefore I always choose C++ over any other language, even if other language is more suitable.