Sirius Satellite Radio

New to this forum, glad to see stock market, sports gambling, and other interesting options... anyhow I just jumped into this last week after doing some reading up on it. Curious to see if there are any other investors in SIRI since it's so heavily traded, or maybe some seasoned experts out there who have good reason to stay away from it.. thoughts on its outlook versus XM, or if this is a good short term/long term buy? At these prices I'd consider adding more on, although I guess from a valuation point of view it might be considered trading too high already...