Although SHIFT 2 is one of my favorite games on Kongregate, I'm afraid this review is going to be rather short because I've already said nearly everything there is to say in my previous commentary on SHIFT.
Both the gameplay and the spirit of SHIFT 2 are quite similar to the original. The gameplay does have a few interesting additions, though. There are now buttons which can rotate the screen 180 degrees without needing to shift, and even buttons which rotate the screen 90 degrees, adding another dimension to the puzzle solving. These buttons make it surprisingly easy to end up going around in circles in some levels, though, so you'll need to pay a little more attention to what's going on. There's also checked squares, which cannot be shifted into but can only be removed by hitting the appropriate trigger. However, while SHIFT 2 may require a bit more thinking, it's still not a difficult game by any means.
The music is different from (and perhaps not quite as good as) the original, but provides a nice background. One welcome addition is a set of achievements, which gives you some goals to shoot for in addition to simply completing the game. Collecting the medals unlocks some additional bonus material (one thing that is promised, for instance, is the option to play as the "classic character" from the original SHIFT). There is also a level editor, which is a nice addition, and comes with a few extra sample levels that you can try out. On the other hand, the proofreading in the game is awfully poor -- there's a lot of typos in the game text (and there's not that much text, so fitting a lot of typos into it takes some work).
Overall, SHIFT 2 doesn't feel that radically different from the original -- it's still a very entertaining game, but still awfully short. But better a small addition than no addition at all, given how much fun it is.