Overall, Supernova is a fun (eventually challenging) play, but not the best DDR out there, in my opinion. (Extreme 2 and Max 2 are my favorites.) I enjoyed the trance/dance songs from previous games, and Supernova seems to be lacking in those. It does have plenty of licensed songs, and I like a lot of them, though they seem a little slow if you're used to the fast-paced trance/dance songs.
The only thing that really bothered me was the unlocking system. You have to complete different challenges (like, "Complete five songs with an A grade or above" or, "Choose (some song) and beat it", etc) and then complete a final "Showdown" challenge. It's a nice idea for beginners, but it's a complete joke if you've played the game before. You have to beat the different challenges at the Beginner/Easy level to earn the Showdown, and then the Showdown is a tutorial of sorts (basic things, like "Don't step back to hit the down arrow, turn your body and step" and "Don't return to the middle of the pad between steps").
I've been playing DDR for about three years, and the Beginner and Easy courses aren't the least bit entertaining anymore. It's a little insulting and a complete waste of time to force advanced and expert players to dumb down their gameplay just to earn more songs. But once you get past unlocking things and crank it up to Advanced or Expert, it's a ton of fun.
As a side note, the dance pad that comes in the bundle is NICE. It reminds me of the pad that came with the Mario DDR game. The underside is thick and rubbery and it doesn't slide at all on our tile floor. The top side is shiny, smooth plastic with a little bit of texture, and it doesn't hurt or stick to my bare feet. I've never purchased a bundle before, so I'm not sure how the other pads were in the other bundles, but this pad is much better than the off-brand ones you can buy alone.