The ultimate goal of the Cooperative Cataloging Rules Wiki is a bit on the radical side. It does not declare that no changes are needed, but rather that the changes needed are much deeper and far more profound than the superficial changes suggested by RDA. In addition, these changes can come from the cataloging community as a whole, instead of being decided by a few libraries in the most important libraries and trickling down to everyone else. The entire Web2.0 movement allows these sorts of grass-level initiatives now and all kinds of new tools can be built.
James Weinheimer, in his blog First Thus, takes the stance that 1) it is going to be very expensive for every library to implement RDA 2) RDA is based on FRBR, which is of unproven usefulness for library patrons, if not for catalogers and 3) RDA doesn't actually do very much other than muck around with 300 fields and spell out a few words which were formerly abbreviated.
I think he's right and he's wrong. The point of RDA, as I understand it, is to free up the data catalogers have been collecting forever so that it can be grabbed by other users and, likewise, to make it easier for catalogers to grab data collected by others to plop into our catalogs.
I do think that his idea that RDA does not go far enough is interesting. I also think his point that catalogers can do it for themselves actually is the point of RDA.
In any case, interesting to think about.