As you probably know, the idea isn't exactly anything new which is a major problem. It is has been done many times before. Would have been more interesting if you could have moved your cannon around and added in power ups etc etc
The graphics were simple, perhaps a little too simple, but I did like the explosion. The blood wasn't terrible but I feel you could have gone a little easier on the filter (you can keep the filter but rather than making the 'shine' a perfect white just make it a lighter red and I would have thought that would improve it 100x straight off). It would have also been nice to see more violent screen shakes when you got hit by a bomb.
All in all, not a bad game just a little too simple for my liking.