Needs more defined graphics.
Not a bad game, definitely has room to grow into something worth playing for the sequel. I love these types of games, but my biggest qualm with it is the graphics. Maybe it's because the orbs are all too small, or because in many cases the only differences are the shades of one color. This wouldn't be so bad if you didn't punish a single bad press by locking up a group of block when you did so. Make the colors more distinct for different levels.
Also more of point concerning difficulty than anything is how harshly you get bombarded with pieces whenever a new level begins. By level 12 or 13 you end up getting some 4 lines worth of pieces dumped on you in an instant, often times almost guaranteeing at least one column became iron.