Really like the old-school feel of the game, it looks good and the controls are well polished.
Game levels are frustrating and fun at the same time as they can be extremely difficult. This is very much by the design, reminds me of Super Meat Boy in the regard. The shared high score system is a good twist and serve as a reminder of just how good some people are at video games.
I haven't gotten very much into the level editor but it seems like a good way of ensuring that new content is added continuously