Huh, I'm surprised that we didn't have a 3DS thread before.
I'm a big fan of Pushmo, so I in fact just bought Crashmo myself yesterday due to the sale. I haven't had a chance to play it too much yet, but as a first impression, the seemingly minor mechanics change (gravity) affects the gameplay way more than I thought it would. In Pushmo, each block was "stuck" to invisible slots in the background, so you mostly only needed to worry about each block independently. But in Crashmo, the blocks now rest on top of each other and yet, somewhat unintuitively, have no weight or friction. This means that if Block A is sitting on top of Block B, you can slide Block B around under it all day without effecting any movement whatsoever in Block A so long as Block B continues to support Block A by even a single point of contact. Pull Block B completely free however, and Block A will immediately plummet to the ground.
In addition, whereas previously you could only move blocks a maximum of three spaces and only back/forward, you can now freely move them around the grid as you please, both back/forward and left/right. On top of that, you can now rotate your perspective to approach the blocks from behind or from either side.
What this all adds up to is that you have a lot more choices and variables to consider in approaching each level, and must think a few more steps ahead. As a result, the game is somewhat more complex and consequently more difficult than its predecessor. Whether you find this to be an improvement depends on your tastes, though personally, I thought much of the charm of the original was how devilishly difficult it could be despite being built on such an exceedingly simple concept.
There's at least one other deceptively significant change for Pushmo players to get used to (Mallo can now move a block without walking along with it, meaning you no longer have to keep at least one space open for Mallo to walk into as he moves a block), but bottom line: Prepare for a somewhat more different experience than you might be expecting. This isn't just a level pack -- there's an obvious through-line to its predecessor, yes, but it seems nearly like a whole new game.
Edited by ThisOneKidMongo - 2/27/13 at 7:37am