While oldskool is perfectly capable of answering for himself, I'll jump in share some of my experience.
The commercials on XM are relatively few and far between - much less than you'd find on regular radio. If you're planning to use XM in the car, there are different methods of obtaining a signal (with varying degrees of clarity). I'm on the bottom rung of the ladder -- I tune my car radio to 87.1 or whatever's lowest on the dial, and voila -- XM radio. Alternately, there are ways to wire the XM receiver directly to your car stereo and obtain better fidelity in the process. Mine already sounds as good as regular radio, so I'm not compelled to bother futzing with it more.
My parents live in Florida, and I've driven from Nashville to Florida listening to the same station without signal loss. That is definitely a selling point to me. And the programming is great. I've been turned on to dozens of artists I never would have heard otherwise, and the tuner display tells me exactly who it is and what the name of the song is.
I'm not sure I'd be particularly interested in paying to have a tuner in the house as well, but for the car I've found it pretty tough to beat. I hardly ever listen to CDs anymore while I'm driving.
