I found the process of peer review to be moderately helpful.
I like reading other people's writing, and it often helps me structure my thoughts better. I found it useful to have access to other peoples take on the same topic.
the comments I received were relatively sparse; I'm sure there was a greater volume to be said about it.
the feedback I left was perhaps too specific, I'm sort of worried that the owners of the papers may find my comments too critical. There were often more to say than i said, but i refrained for fear of offending people or appearing a nit-picky knowitall. On the other hand, I wish I had received some very detailed, nit-picky comments.