It isn't hard to try it out to see if you are suited for a standing desk; TreeHugger Mike did it with Kleenex boxes. You have to give it a few weeks to get adjusted to it. Mike wrote that it took a while, but that it changed his life:
I have to say, the first 3 and a half weeks were a mixed bag. For a while, it felt like I was trading a set of problems for another one. My shoulder and arm were feeling better by the day, but my feet were killing me. I knew it would take a little while to adapt - especially since I wasn't used to standing for extended periods of time - but I didn't expect it to take over 3 weeks. The good news is that around the 4th week, my feet stopped hurting and my RSI problems have stayed mostly under control.