I had an interest in a Boxee box, until I found out that apparently it doesn't have Hulu (because of Hulu, NOT Boxee.)
I had thought it would be a nice alternative for our guest room which has internet access but no cable outlet. I also have an Apple TV in our living room (where I have cable), but the problem with solely having an Apple TV and no cable is the availability of content. With Hulu I would have been able to watch a wide array of programming at no monetary cost.
An Apple TV is great for all the digital media that you own, but not for finding the random thing to entertain you for 30 minutes or an hour.