It's a cold, dark, scary place with vultures and spiders and small flesh-eating insects.
I know the trepidation, and the fear that one sucks so bad there'd be a public flogging and humiliation. We try very hard to make that place a friendly, informative, educational exchange. Sometimes people do abuse it, but by and large I think it's a good place for people to get ideas on how to improve. We should all realize that critiques are opinions -- they don't necessarily mean your writing sucks if someone doesn't like it.
I think there are many ways a writer can improve, and putting your work out there for critique is one. Just think about it -- eventually, someone will have to read your work, whether it is an agent, an editor, a reviewer, or a reader. So somewhere someone will criticize your work some time. If you show it here, you may get the good suggestions on how to improve a piece, and get the motivation to polish it so that it doesn't stink in the hands of a prospective agent or editor.
That's how I look at critiques. It's not easy to detach yourself from your work, but if I want to get published, I have to. I want to look at the work and see how I can improve and polish it to shine. Sometimes just a little nudge is enough to push me. Sometimes it's also good to just throw something out there and see if it works -- if someone says, "Not really, full of holes and inconsistency, etc." then I know I need to keep working on it.
Give SYW a try.