Ok, decent.
I had troubles with the game even loading into the next stage and freezing when the AD was supposed to hit.
So had to reload for every level. I have flash 10.
I switched to Firefox instead of Google chrome and this problem ended.
I don't mind the ads, since you can skip after like 3 secs.
The sniper level is what brought my fun to an end.
I have a feeling you need to combo the enemies before hitting the
master alien with your own sniper to get further enough to beat that level. Didn't have the patience after working around the bugs (minor, to me, though).
Fun game. Please make more and I'll be back when someone posts a walkthrough of the sniper level :)