Clearly a game to be improved in a post-jam version! I'm a big fan of puzzle plateformer and this one works completely and could really be extended to more levels or even new mechanics.
If I may offer a word of advice, perhaps revise the player's deceleration a little? Being very slippery can make the game a bit punishing. Or reduce the collision polygon of the spikes a little to be a little more forgiving. In my opinion, this would allow you to put more emphasis on well-designed levels (which you seem to know how to do) and allow players who aren't platform pros to still succeed in levels once they've figured out the right path to take. But it also depends on the game you want to make and the audience you're aiming for. A game with a lot of sliding and uncompromising collisions will surely appeal to players who play “Super Meat Boy” and like to be pixel perfect.
In any case, it's currently a great game, and I'll be delighted to see it evolve. Bravo!