Are they worth it? Only you can decide if they are worth it to you.
I've had mine for about 3 years and use them every day. I do feel they help my legs feel less trashed the next day. I'm currently in them now as I type this. 70 mile ride this morning and have a long run tomorrow. I won't feel the effects of todays ride during tomorrow's run.
People have mentioned they have used them right before workouts and have noticed benefits. Personally have never done this (not enough time for me).