I'm a fan of Tetris but I found it really hard to get an intuition of what I was aiming for in this game. (I don't even really understand what "connect numbers in a row" means; obviously it's something to do with 1-2-3-4 lining up, but I can't explain why sometimes half the level disappears and other times it just keeps building up and up.) The best I can do is just play Tetris normally, and occasionally things disappear and it's not clear when that will happen. I have nowhere near the mental capacity to be looking at the numbers while playing Tetris.
Also, I found it very "slippery" - I would often be trying to place a piece in one column and it would go one space too far, for some reason (I think the repeat delay is too low perhaps).
That said, this has awesome JUICE. I love the look of it, the shaders, the effects, the audio. It really comes together visually.