I don't know about the '$55 one time subscription' (I think it is a yearly charge) Having said that, it is for a year, which means along with the tour you can watch the Giro, Tour of California, etc. I like it. It's one of my few TV indulgences. Now, whether it's 'worth it,' all depends on how much you like to have an excuse to sit and watch bike riding, rather than going out and doing some. In Tucson, in the Summer, If you're not out there riding by about 6 AM, you're toast. Unfortunately, the 'live' coverage is not finished till about 9 AM, so July doesn't see me out on the roads too much.
However, you can watch any stage pre-recorded. So you can go out on your ride and then watch a stage.