I am a lawyer, and not a particularly jingoistic American one. I go back to the US fairly frequently on business or for visits, but I cannot really imagine going back there to live, at least not anytime soon. There are many aspects of American politics and life that have grown very foreign to me. Although I enjoy my visits there to visit family and friends, I went there twice in 2005 and realised during the second trip that it was beginning to grate. In future, I will probably not go more than once a year.
I would nevertheless not advise a client to renounce US citizenship unless there was a very good reason for doing so (there could be reasons having to do with criminal law or possibly because of certain kinds of dual citizenship issues). Renouncing your US citizenship would be radical and permanent, and could come back to bite you someday in a way that you cannot now anticipate.
Is this a political gesture, is it because you have bad feelings about things that happened to you there (i.e. is it personal)?