Excellent concept, mediocure execution
I do like the concept of a cylinder tetris, but there are some quirks that has to be resolved if you plan on a sequel.
-The controls are slow. Slow as in they are not that responsive. At least in my style, I constantly tap the buttons to move, and in this case they only work about half the time. Like scqjayce said, puzzle games, especially Tetris rely on fast and responsive controls. Gameplay-wise, this is the biggest grudge I have against the game.
-The depth of field is pretty poor, as in the radius of the each circle inside of it is the same distance from their respective outer. Commonly known fact that an object appears to shrinks slower as it gets farther away (that's the best I can word it). Read up on how perspectives are drawn, especially highway tunnels. Look at some pictures of them, all the lights are technically the same distance apart, but from YOUR view, how far apart do they look like? This is a big problem to me in terms of I'm an artist and it also made it tough for me to line up the blocks, which leads into some suggestions.
Suggestions
-Improve the depth of field, it'll look better.
-Alternate the line colors, it will make it a lot easier to line up the block to where you want it.
-Improve on the controls to have it respond quicker.
-Also add some music in the background. Even the generic Tetris theme would work since it's easy to listen to while playing, and not too distracting.