I like them for the sense of community and the designing within guidelines aspect (it's a fun challenge), but there's a lot of unkindness and elitism that's actively turned me off more than one species, and I don't like not having full rights to my character (as someone said earlier in this thread).
A lot of people in CS communities have been pretty rude to me about my art, too. I don't think anyone's obligated to accept my offers, but I've noticed that I tend to be the only person making offers who doesn't get "your art is lovely, but..." type comments so much as hard no's. Someone for an exchange I participated in for a species insulted my art to my face. Someone else just kind of jerked me around about offers for months, then... insulted my art and my personality to my face. I get ignored constantly. It's very frustrating when you do go in looking for community, and the community is like, "sorry, you're not good enough!".
There's also huge issues with cliques and favoritism, and bringing it up as an issue gets dismissed because the people in those cliques tend to be mods (this isn't a dig at a specific species if you're thinking of one, it's a pattern I've seen across multiple).
Overall, I do still like them, but it's very easy for species communities to breed jerks.