Carlene:
Thanks for starting this thread. It's such an interesting subject. I am mixed about critique groups. I whole-heartedly support them, but I prefer the online variety if there are written guidelines about downloading and general critiquing, and if it has a post and critique schedule to focus everyone. The beauty of an online group is that you can do it in the comfort of your home and any time you have a free moment to comment on someone else's work. I became so tuned into them, that I started one through Yahoo for my local chapter of Sisters in Crime, replete with private folders, message board, and a chat room. It still has the same original three members, and while new ones have joined, most don't stick around more than a few months.
I've tried the critiquing circles, but find them more time-consuming. Sometimes tempers flare, people invariably quit, and it's hard to attract new members who can commit to a regular schedule. I feel I benefit most from author mentoring. I write adult suspense-adventure, and was fortunate to be tutored by an author of over 60 YA mystery/horror books. It turned out to be a fantastic match and I credit her with keeping me on track.