Not too bad, but not all that great either
It's a great concept, and I enjoyed the music and even some of the game play. However, it was a tidbit too easy to beat. I understand though, that coding can get difficult, but that's the point of making something, putting a lot of hard work and effort into it. I see you put some effort, but not enough. The game play, during the levels, the blocks moved too slowly. In normal tetris, as you progress into levels the blocks move much faster. That's something to work on.
I also understand you were trying to have "different" blocks. But there were some points when I couldn't see the blocks because they melded into the background, so I basically had to wait to see something move to be able to use it.
Just keep trying, I bet your final product of this will be great!