We have used it on our sailboat and it works great. The appeal to me is the ability to get the News and talk channels. I have XM, so its CNN, CNBC, Fox etc. As far as music, there are so many ways to get music without dealing with satellites that I don't see the need.
I wouldn't worry about the long-term profitability of the services since the majority of your expense is the monthly fee, you would just just stop paying if they failed. Eventually they may merge. In reality the problem they are having is recouping the huge initial investment of developing the systems. The satellites are already in the sky - so the companies will someday declare Chapter 11 and reorganize if they aren't able to turn it around.
Twenty years from now you will be more disappointed by the things y%^&*.....oh never mind. 90% of the people on sailing forums already use that as their signature! I'm not a conformist.