vs. Tetris is fine and all, but there's just nothing here outside of playing a relatively slow game of Tetris. You filling lines doesn't negatively affect your opponent aside from the tug of war at the top, and it doesn't seem like there's much of an incentive to build up and fill in 4 lines like in normal tetris or most versus Tetris. The upgrades are expensive and sparse and, to be honest, I don't know how many people are going to be interested in the game long enough to actually make use of them.
There's something you can work with here, but in it's current form, it's too slow and there's not enough to the versus elements.