I have a Needak Rebounder (which the UR is based on, and which I got from UR before they had their own model). Even though there are long stretches of time when I don't use it, I would buy it again. I like to have a variety of types of cardio, the more the better, and rebounding is good to add in with step and kickboxing.
More than specific UR workouts, I use it for modifying other workouts (Leslie Sansone, which I bought specificially for the music and beat and company, and which I modify 'up' to use on the rebounders, doing high impact moves like those in MIC or jump rope moves in other workouts). I just got it back out recently, and did a CC workout on it. I plan to do so regularly for a while.
I can't run or jog or definitely not sprint on the ground (that's how I screwed up my knee years ago), but I can do all of these on the rebounder, which makes it a good way of getting a more intense exercise without the impact).