I think the problem alot of people have is that Cannonical isn't listening to user input on Unity. They have their design brief that they've come up with, and their target (OS X). Meanwhile, traditional Ubuntu users are being displaced by the lack of community input and feedback.

In this way, Unity could end up hurting Ubuntu's growth much more than it helps it. Judging from comments online, many people are recommending Linux Mint to family members where they would have once recommended Ubuntu. There's no real evidence of this happening yet (distrowatch isn't a definitive source), but I think Canonical is playing a dangerous game in how it is interacting with it's community on unity and the issues around it. Some of the uglier public conversations/posts by Mark Shuttleworth and others only highlight the danger.