Unity remains controversial and I have mixed feelings about it myself. I think that application discovery is more difficult when using the dash than it is using the previous pull-down menu system. Changing workspaces requires an additional step in Unity and the placement of window controls and menus in the top corner of the workspace is awkward at best.
But on the other hand, I get what the designers are trying to do. In addition to making the user interface more touch-friendly (because it's the future du jour), it attempts to reduce distraction on the desktop and make your work easier to focus on.
I have 12.04 running on my laptops and netbooks (it's a good fit for netbooks) and will be upgrading my main desktop to it soon.