Slingbox Solos have a history of going down because of bad capacitors. If you're good with a soldering iron, ffour bucks worth of components, and you're back in action. (I repaired my 18 month old refurbed Slingbox last weekend and brought it back to life.) If you're not handy, Slingbox's customer service is okay as long as the warranty lasts. After that, its teh suck. You have to pony up $30 just to get them to listen to your complaint.
Also, there are reports that there may be issues using the thirty dollar Slingbox software for anything other than the 4G. My partner has a 3GS upgraded to the newest firmware and it seems to work okay, though. Luck of the draw? It works fine on my Evo, but the interface isn't as pretty as the iPhone version.
A few other little quirks that might not have been noticed: You can only watch through one remote device at a time. If you're watching in Dallas and your partner in Seattle wants to watch too, one of you is going to have to bail.
Also, this will control ONE component. It's not designed to switch back and forth between, say, cable and DVD. Not an issue in my case, but others may find that annoying.
All in all, the slingbox is a great little toy. I use it a lot.