I'm a devout Catholic sometime-scholar and I find the CE invaluable. Doctrinally (as far as I can tell, not being a theologian) it is unimpeachable, and I find it particularly useful (as you pointed out LarryLied) in its even-handed approach to everything it covers. If I wanted to know simply what unitarianism or gnosticism was all about, without all the revisionist garbage, that's where I'd go. It doesn't refrain from making moral and doctrinal judgments (I remember it said that islamic ethics were "far inferior" to that of Christianity and Judaism), but in no case have I found that it is factually inaccurate. It does an excellent job covering controversies and objections to various doctrines.
Most of my research revolves around Native America, and have numerous times searched for some obscure tribe on Google only to find it mentioned in the CE. Some of my favorite articles are the ones on Cosmogony and the Pre-Columbian Discovery of America.
This discussion reminds me of something...Archbishop Fulton Sheen said that a Marxist told him once that the best and clearest description of Marxism he had ever heard came from a papal encyclical (which was, no doubt, condemning it).
Thanks for the links. It is a large resource and pointers on where to look for the good stuff is appreciated.