I can only speak for myself, but yes, for me, the GeekDesk is great and worth every penny. Have had mine for a couple years now. The main advantage of motorized, though it sounds "lazy," is that you can change positions often and easily, so...well... you DO. I use a few different chairs (all < $275) -- a no-name adjustable office/swivel chair, a bar stool, and a kneeling (aka "balans") chair -- and change up my working position throughout the day. That helps a LOT (back / neck / shoulders, energy level, etc).
I want to get a nicer task chair eventually (preferably with headrest; no idea what brand yet), but I've got NO regrets on having upgraded the desk first. Highly recommended.