Some moderate updates to the gameplay (primarily with the new rules and roster changes), but if you're on any kind of budget or aren't in a rush to play, it's probably best to wait for next year when the series shifts to the current-gen.
Sleeping Dogs is great, and if you haven't already bought the content previously, it's an excellent deal. However, the Definitive Edition manages to leave a lot of relatively harmless, yet annoying, bugs in place which is a letdown.
If you can only have one Skylanders game this year, you'll probably want to shoot for either the PS4 or the X1 version. If you're wanting a portable take on Trap Team, the new tablet version could be the way to go, or, the 3DS one offers a pretty solid experience with some caveats.
Whether this Gauntlet is just like the original one or not, I don't know and it really doesn't matter. But playing this game with others has proven to be a blast, even though it's not very deep or long. For $20, you can do a lot worse, but to find a game this instantly accessible and fun, you may be harder pressed to find.
If you aren't into JRPGs I won't say that this game is going to change that for you, but as someone who rarely plays the genre, Fairy Fencer F was surprisingly agreeable with me. It's another solid addition to the PS3's library of JRPGs, and I recommend making an effort to check it out.