It's enjoyable until you get colors that look the same. red/orange and blue/slightly lighter blue make it very annoying.
Weak sound effects, no music, and it doesn't say what colour comes next (typical for these type of games) means only 3.5/5. Good game, just has room for improvement.
Very good, I like this game. I think the only thing this game needs to have my 5 stars, is a music.