I consider myself a power user, and I like unity. I've been using Linux exclusively for about 10 years now, and I run my own mail server, database, web server, and I tinker with sshd config files, send my emails with gpg--the works. I had switched from Debian to Kubuntu about 2 years ago, and I've used KDE from 3.1 to about 4.3. I switched away from KDE because it was slow with compositing and switching windows.
Now unity does have its issues, but it has many strengths. The 2D interface is built on metacity, and it's very fast. One thing I like about unity is that the title bar serves the dual purpose as the status bar, saving about a half inch or more of vertical screen space on every window. I use the keyboard extensively for window management, and not having a title bar in addition to a status bar is a welcome change.
The launcher stays out of the way (behind windows), and it can be easily used to launch applications with a keyboard. A number associated with each application on the launcher panel such that it'll either launch a new instance or switch to an existing instance instantly when pressed. For instance, I can press Win+1 from anywhere, and it'll take me to my browser, or open a new browser window.
That said, unity definitely still needs work when it comes to managing a lot of windows. My typical workstation has 9 desktops with up to 9 windows on each. For applications, such as Gimp, that use multiple windows, minimizing and accessing different windows can be a hassle in unity. There are also some stability issues in unity.
However, I do think that unity 2D shows great promise, particularly for users that are adept at keyboard shortcuts.