A most impressive game.
This game has great music that is well placed in the game, great challenge and brilliantly fun.
Even though I write the above on behalf of my friend there is one thing that ruined it for me... It's not your fault but just take this suggestion. I'm colourblind and with this means this game posses an additional challenge for me that makes me have a 20% chance of stacking 3 in a row with 2 colours that look exactly the same to me. There's two ways I can think of to solve this...
1st: when the next block appears either have some mini arrow on corresponding blocks or a slight glow to them. This does however decrease the difficulty with all players.
2nd: make little symbols on the blocks for additional matching power.
With both of these you could have the player decide in the menu whether to have it or not.
(special thanks to my friend for stopping me from raging in this review and calming me down... rated score and the first 2 lines is from him.)