Excellent; could be even better
I gave this 5/5 because it was incredibly fun--only 8/10 in this review, however, because it wound up feeling a little lacking. If you added in some of the suggestions below (different powerups, life-ups, debuffs), it could be even more exciting.
If you add in any extra doohickies, slow down the speed-up (huh) so that the player has more time to get accustomed to the multiple aspects.
With or without additions, this is a very solid game that succeeds in achieving an old-school arcade feel.