My initial impressions of the game were positive, but the more I play it, the more I dislike this game.
My complaint is that by the halfway mark, the game feels way too random. The gun AI seems to occasionally take naps where it doesn't respond to enemies in range and sometimes shoots at empty space (completely missing even stationary targets). The difficulty isn't at all forgiving, so one misfire could mean the difference between winning and losing. Similarly, you can't control where the cows appear when they're added - if you get a loner by itself, that's often enough to force a do-over.
I don't mind difficult games. I enjoy TD type games that give a fair challenge, but there needs to be predictability. I don't mind losing if I went with a bad strategy; I get frustrated though when it feels like I lost simply because I can't depend on my towers to actually do what they're supposed to do.