The good folks at SlickEdit® hooked me up with a review copy of SlickEdit 2008 Professional, and I gotta tell ya I was pretty surprised. I didn't really know what to expect. I guess I just expected a less feature-rich Visual Studio, but that's definitely not what I found.
First of all, I wouldn't consider SlickEdit to be a competitor to Visual Studio. It's more of a multi-purpose polyglot programmer's editor on steroids. First, on install, it asks about your editing environment emulation. This is a great way to ease into SlickEdit from another editing environment (for me Visual Studio).
Then, it asks about language Tag Files (which is basically how the environment will handle you chosen languages like syntax highlighting, compiler options, etc). Then it starts on a long journey of building these Tag Files. This was really the only unpleasant part of beginning to use SlickEdit. It seemed to take an inordinately long time to build these files. Chances are there are more things going on than I am aware of in this step of the set up process. Nonetheless, you only have to live through this once.
Once this was done, I moved directly to the Tools -> Options. I was able to setup my color scheme pretty close to the what I like using some preset color schemes. In Visual Studio, I use Jon Lam's Vibrant Ink Port for Visual Studio. It's very easy on the eyes. So just choosing the "Black" color scheme got me pretty close.
I then saw Tools in the tree on the Options panel and opened it up. I saw Version Control Setup and was able to add Subversion by just clicking setup and pointing it to my Subversion executable on my machine. Couldn't have been easier.

Cruising around the Options panel some more, I saw the Languages Item in the tree view. I think there is probably a choice for every programming language ever used (what the hell is YACC?). There are so many options in the Options Panel I could write a book about just that panel.. but I'm not gonna. Suffice it to say, that if you want to program in ANTLR, you can use SlickEdit. :0)
Finally, I sent an email to SlickEdit and asked about setting up MbUnit unit testing within the IDE. This tests two things: whether or not I could do it (it wasn't obvious from the menus) & how fast the respond to support questions. I sent the email at 3:22PM and got a response at 4:33PM, so that is a damn good response time. They actually answered my question, too. I was able to setup MbUnit to run from within the IDE, by setting up a new menu item and pointing to the MbUnit executable to run my tests. (My tests didn't actually run, my command line arguments were not correct, but I didn't want to take the time to figure out what they should be and that is not a problem with SlickEdit, it's a problem with me. PEBKAC)
Even though, I'm not going to stop using VS in favor of SlickEdit, it is definitely going on my machine for programming in other languages that don't have a good IDE. All in all, SlickEdit is pretty... slick.
~Lee