Decent
The game was somewhat difficult, but I eventually found a good plan of attack to get me through. Was laggy at times, and sometimes dead-aim would just miss the bird the shot was intended for and hit something behind it. But if you find this game unbeatable, try this:
Skip every other gun up to the Flamer. Also, skip the bazooka and sniper rifle. So that is Musket - Machine Gun - Flamer - and then the rest. Sticking with the gun you have longer will from what I've seen keep the game from generating the stronger birds until you can practically deal with them. Following that, along with decent aim and money shouldnt be a big issue.