Well...
I think it is an interesting Idea, but I don't think it worked so well. The sequence was never so much an issue for me, however there were several times in the first level set that I failed out just trying to read the numbers. The colors blended too much. Also the difference between some of the 'same time' vs. like a ms apart Isn't what I would call a sequence issue so much as ones choice in calling events seperate. I don't know if it looks more distinct on better computers but on mine the last 3 digets in the first level sequence appear to fall at the same time.
Also I do agree with what someone else had said about the purple looking blue. That is until you actually see the blue. Blue did not appear in the color sequence until the last level for me at which point I simply went 'Oh, so that is why they call it purple'. I guess the theme of the point is you should either change the color of the words to match. Or set the swatches to match the color of the words. By the by on that same note the swatch for the red and orange look the same to me.
I think passing the first and third level sets were really more about trial and error and discovering the ideosyncrasies of the game than they were about any sort of skill. The second and fourth level sets flew by and proved that in my mind.
Furthermore I did like the music, I just didn't want to listen to it while playing the game, you should be able to turn the music off before starting the actual game so you don't miss action or loose time shutting it off. Along those lines it would be nice if your buttons (such as the music, menu, replay, etc.) were buttons rather than clickable text. When time is a factor you don't want to click somewhere and realise that the click did nothing because your mouse wasn't in exactly the right spot.
Also on a last note. The timer should not run between levels. When the game is not running you should not have to rush if you don't want a bad score. And those are my thoughts. I know some of these issues have been touched before but I just wanted to include a full set of my comments on the game.