This is still the same show - if you liked it before, you'll still like this. If you didn't, this probably wont change your mind. The humor hasn't changed much in its nature, but they still find new jokes to tell so the show still feels fresh and new. The intros to each episode I think were better this season than any previous season.
The Blu-Ray plays without a problem once you get it loaded, although load time is a little longer than other blu-rays. Features also include access to online streaming of season 7 episodes.
In general, Blu-Ray for shows doesn't have a huge picture/sound quality difference from DVD, but in this case the difference was appreciable. The picture especially was much improved - far crisper image.