Oh man is it. There's been only indoor riding recently since the temperatures here in the northeast have dipped yet again into the sub-freezing realm, and we've been subjected to a couple more ice storms. It's bad enough to wake up to ice on the car, but it's further demoralizing when you were hoping for some good weekend weather to get out and have a nice, relaxing (but brutally hard) road ride. It really doesn't bode well when you can't walk down the side of the road without feeling like you're walking across the ice at a (insert your favorite hockey team)'s game.
On the other hand, it's easy to do structured workouts on the trainer. The Power To The Pedals program from Roadbikerider.com is a great program, and it's so easily done on the trainer as well. It's actually funny, when you think about it. We derive no joy from riding indoors on a trainer, since you really don't go anywhere at all, yet doing a workout program like that, in conjunction with watching some good TV (like last year's Giro) can make the hour go by incredibly fast.
Oh, and some good company helps as well.
Just think, mountain bike season is almost here.