A little bugged...
The graphics aren't very good, but in a game like this, graphics aren't a major concern so that's not a big deal. I know you said that the button delay was intentional, but it makes the game impossible to play at certain times... when a lot of enemies are trapped in the small area behind the pot, if you don't have enough special bar to take them out, you are guaranteed to get hit a few times and perhaps die because they roam around so quickly and you just can't block fast enough.
I did find a rather game-killing bug, too... I played through for a while and finally died due to shield lag. When I restarted, no enemies would appear. I still have the game open, and I walked around for a full two minutes back and forth to see if enemies would spawn, but none ever did. I don't know if this is a one time bug or if this is what happens on every replay, but it's a rather significant problem in my opinion.
The only suggestion I can make, other than fixing the problem I mentioned above, is to lessen the buttonj delay slightly or remove it altogether. Why was it intentional? When the field is flooded with enemies, the button delay makes the game impossible to win. Then again, I don't know if this game can actually be won or if it's just endless.