Well, I guess I'm the only one? I've been paying for the past few years. I ususlly just do two 2 month shots to cover Dec-March. I've found that their forecasts have usually been very good, and often better than weather.com (which is pretty crappy IMO).
I like the fact that they're truly resort specific, and give temps and snow forecasts for various elevations on the mountain. It also seems that they've gotten better over the past year with more up-to-date forecasts then they've had in the past.
I'm not sure, but I believe that the only thing you gain by paying, is the extended forecast. The 1-3 day forecast is still free. So paying for it depends on how often you need to plan trips that far in advance.