Atleast if you like Rock. The closest thing to shit rock I've heard on their their rock stations (other than the one that's supposed to play shit-rock, Hair Nation) is the occasional "Panic! at the Disco" song on Alt Nation or "Papa Roach" song on their "extreme" station, forget what it's called. Other than that, it's all gravy. No fuckin Nickelback, no fuckin "Hinder" and of course no Creed.
Basically 5 and a half GREAT classic Rock stations if you include half of Buzzsaws music and Little Stevens Underground Garage. First wave plays awesome 70's and 80's Alternative/proto-punk (lots of Bowie, REM, Smiths, Cure, etc).
Also they've got an Indie Rock station called "Left-of-Center" that has a great morning show hosted by Jake Fogelnest from Squirt TV, that you can listen to if you don't like Howard or when Howard is on Vacation/taking a break.
so, that's my quick off-the-top-of-my-head spiel.
Sirius also offers a free 3 day trial whenever you want, with most of the stations I just talked about (not stuff like Howard though)
http://www.sirius.com/servlet/MediaPlayerRegistration