It's not a Toy, it's a tool. Just like every video-game development engine it has it's flaws. The most basic flaw is probably the performance on mobiles. But guess what? IT'S ALREADY BEEN SAID SO MANY TIMES. The main reason someone will have a bad time on mobile in the beginning is because they haven't done their homework, on how to develop games for mobile using C2. Using physics? You're gonna have to be frugal, other than that though, it's been quite great for me.
Changes? I don't think there have been MAJOR changes, to the point where someone has to re-build their entire project. Everyone in this thread isn't against you btw, we're merely trying to inform you.