Adding levels to a arcade-y game like 2048 is a double-edged sword -- it's very nice for people who have little or no experience with the original, but for people who have played a lot of 2048 (or Threes) the early levels are tedious and not interesting. This is compounded by the fact that some of the levels are too large, making the goals extremely easy to do. To be honest, I'm a little curious why you didn't add a "classic mode" that plays just like the original? It should have been fairly easy to add...
The visuals were good, especially the movement and merging of the blocks. The idea of having a different background every few levels does a lot to break up the monotony. The sound effects sound nice on their own, but I would recommend they be shorter. If a sound is going to be played literally hundreds of times, often in rapid succession, it should be a fraction of a second long.
Overall a good effert for a first time jammer :)