Shan, I have Sirius. Mine is portable and I have it in my WRX, but there's just no good place to put it. So, I have it in the glove box and leave it open and change channels with the remote.
If I had to do it again, I'd get one that goes in the dash, without question. Portability would be nice, but there are so many channels, etc, that unless it's right there in the dash, it can become a real distraction when you're driving.