A lot of them have heating and crashing problems apparently. The general read is that the situation is worse then with the original Xbox, but then again all of the first generation consoles suffer these problems... except Nintendo (excluding the NES era).
Controller wise, can someone explain to me what's so great about it? The D-Pad is akward, the buttons are no longer analogue or have pressure feedback, the sticks lack ruber coating and have a drastically reduced force feedback system. It's like an econo version of the original Xbox controller in every aspect.
That being said, it's not a bad controller, it's just not a huge step up or even really a step up imo. It's smaller and has a slightly nicer shape (while feelling less natural when you hold it).