OK. Wow. I'm going to make a list of positives here.
1. I liked the music. It might have been a bit loud, but since I seem to say that about EVERYTHING I play, I'm starting to think it's just me.
2. The levels were fun. Really fun. And a good number were actually hard. I liked that.
3. There were no major bugs that I found. The animation and audio overlay was flawless.
4. Your gun shoots rainbows.
5. This point gets two numbers. Your gun shoots rainbows.
6. Rainbows that DO THINGS.
The bombs were able to be used... interestingly. By that, I mean that it hardly mattered what I blew up it seemed. For example, in the Packaging Room (right after you run underneath 2 doomed puppies) there's a little conveyor for decoration. I was able to blow a hole into that room and try to get the puppies that way - meeting with a solid wall on the other side. Oops.
Unless I missed it, there was no quicktravel feature. That may be a bit much to ask for, but I really dislike having to re-solve puzzles to go across the map to places I missed. I also don't like how the minimap doesn't quite show you the way back.
Not sure if intended, but the final boss' "attack" can be effortlessly dodged if you stand as close as you can.
That's all I can think of right now. I really enjoyed it - probably wouldn't have dumped 3 hours into it if I didn't.