Not a bad game
It does a lot right with some varied enemies to control and puzzle games are always fun when done right, like this one. However, I feel more could have been done to make it even greater. For example, a larger variety of humans to infect would have been great. Think of all the variety of abilities you could create with that. I also feel that if you control a human, you shouldn't get shot at by other humans. It's a stealth thing that I think would have been a cool way to go about it. Then develop a character that is able to see through you clever disguises.
In short, good. Even great. But much room for further improvement.