I've only been to one conference, and while I wouldn't call it a negative experience, there were definitely elements that made me feel that perhaps it was a bad fit. Here's a list of my general impressions, so I don't know if it will help, but for what it's worth:
Socially, it was interesting because I was way (way, way) younger than most of the other attendees. I also had a different kind of education, different reading tastes, and even though it was a genre conference and I write fantasy and horror, it seemed like I write different stories. There was nothing bad or disappointing about these differences themselves, and I met a lot of really interesting people. However, I often felt that many of the conference-goers were inclined to treat me more like a child than an adult. I believe that it really was out of kindness and a desire to mentor, but I had well-meaning people explaining self-explanatory things to me constantly—about writing, publishing, networking. All kinds of people were cautioning me against various newbie mistakes and giving me writing tips, and it became kind of exhausting after awhile.
The agent and editor panels were wonderful and entertaining. It gave me a chance to see a side of publishing that I don't know a lot about, and to really get an understanding of the way people's sensibilities differ across the board, just like with anything else. I liked listening to editors and agents talk with each other about projects and concerns and what they get really excited about. This was the part that seemed most “worth it” to me.
I was not at all impressed with the workshops. Because each generally ran only about an hour, the information was very cursory, and mostly reiterated things I've either read on my own or studied in school. A lot of the books that the presenters used as examples were books that I hadn't read, or else books that I don't particularly like and certainly don't think are shockingly good (Janet Evanovich, James Patterson, Laurel K. Hamilton). I know that's a matter of taste, and these are books that sell extremely well, but I generally didn't find what the presenters had to say about them informative. It was especially frustrating, because I would get very excited about the titles of the workshops—they promised so much—and then by the end I would usually wind up feeling cheated
Although you do find all different types of people everywhere, it seemed that the conference proportionately drew more people who were likely to monopolize discussions, argue senselessly with the presenters, and generally exhibit very poor social skills. This does not at all represent the group as whole, but these types certainly made themselves more visible than those who were content to listen and behave in a more civilized way.
It seems like there are many writers who enjoy conferences, get a lot of out them, and make useful contacts. My experience just doesn't happen to mirror that. I'm glad I went, but I don't think I would want to go to another one. In the end, I just didn't feel like it was worth the money.
P.S. The food was excellent, though.