I just played this and its quite addictive. Everything ran smoothly and the presentation is quite good, especially like the font used.
Here's one or two things I would change:
-On the menu you screen you should set some default entries for the mode, difficulty etc.
-Also you should store what the user picked in the menu options to a file, so the next time you play the options are set to how you want them.
-In colours mode sometimes it was hard to see if the block was repeating or not, maybe make it more noticeable
-Seperate the red and orange colour blocks (at the bottom) as its hard to tell the colours apart when next to each other
-When one sequence is complete, instead of making the user press ready, just countdown 3,2,1 (fast) and go ahead with the next sequence. If the user wants a break add a pause button in or something
-Put an exit button on the menu
...and wow that game is fiendishly hard especially in blocks mode when you get to about 7+ blocks - Good work I like my games to be hard