The first gen was absolutely god awful from everything I read and heard. The second gen has been nothing but good to me.
I play some games occasionally and it can get very hot with the dedicated graphics card running, but I mean it is a laptop running some pretty demanding games, so I feel like that is reasonable. I use a cooling pad and it deals with the heat much better.
The trackpad is great and has multitouch, not quite as nice feeling as apple's, but about the best I have ever used on a PC. The speakers are awesome, they get louder than any laptop I have heard with good bass and sound quality, for a laptop. The beats audio was a complete gimmick on the first generation, but they really got their shit together for the new model.
My one largest gripe is that there is some keyboard flex on the left hand side, but I don't really notice it that much (and I don't type too much, not a journalism major or anything). I knew about it before I bought it, from reviews, and it wasn't a deal breaker for me - it still isn't.
After a year, the battery doesn't last quite as long as it used to, but that is to be expected from any electronic device I've ever used pretty much. It still lasts a good amount of time though and I don't usually have to worry about it dying on me.
I really like mine and I think it is a great value (although not cheap) considering mine has a 1080p screen, aluminum body, dedicated graphics card, great speakers, one of the faster i7s & 8GB of RAM.