Many writers, at some point, want to join a writing group. Having seen many people come and go, I wonder sometimes what people expected when they joined.
A critique group is just that - it offers critiques. Sometimes people receive a few critiques and then disappear. Others complain or completely ignore what people have said in favor of their original work. Sometimes the writer is right, but when you're in a group of people who've done this for a long time they're honestly trying to help people excavate that dingy bronze urn and shine it to a museum quality polish.
Two people I know eschewed virtually all suggestions and critiques given to them and self-published their books. Both were terrible, but with enough time spent learning the craft of writing, they both probably could have made it with a publisher.
Don't expect them to squeal over your story and be fans - you'll be more than disappointed. Do expect both good and bad points to be laid out for you. If there's a consistent thread of complaint, there's probably a good reason. The people who spend their time in critique groups are the readers and book buyers you'll one day want to attract. If your test audience can't figure it out, odds are the rest won't, either.
In all honesty, I've hung out with many different types of writers, and the ones who have taken the time to write their story, rewrite it even when they want the plot to go a different direction but the character says otherwise, takes the time to learn how to properly erect sentences, which give way to paragraphs and beyond, who go over their stories and truly listen to what makes it better, and are not subdued by the mountains of rejections they get - these are the people who succeed. The ones who try. The ones who earn it.
I'm grateful I'm in a writing group - besides giving critiques and suggestions like pros, watching other writers grow and hone their techniques is gratifying. On top of it, when other writers succeed in getting published, you get to carry the high along with them. It gives me hope for the end of the long-ass editing tunnel I'm currently in.
Which I am still enjoying. Editing is easy now that I am getting a grasp on fictional mechanics and structure.