A couple others I remembered...
Twilight Realm by Christopher Carpenter
A group of friends are sucked into an alternate universe not unlike the pen and paper game they play. They are sent there to slay an evil wizard, and as part of their quest they become the characters they've always wanted to be. Essentially, they become polar opposites of the people they really are. They find out along the way (or so the ho-hum interactions lead you to believe) that being someone else ain't all it's cracked up to be. I guess he's supposed to be a highly accomplished author under a different name, but he really wasn't all that good with this book. The only reason I was able to finish it was that it was incredibly (mercifully?) short. It would have been better if it were longer, deeper in the character department, rid of about 75% of the pointless adverbs, and smoothed out. It really felt like a first draft that begged to be so much deeper; god knows it had the potential.
The Big Time by Fritz Leiber
It won the Hugo award for best novel.
It's critically acclaimed.
It's got a decent cult fan following.
It made me want to shoot myself.
Okay, so I acknowledge that Leiber did something right with this novel, otherwise it wouldn't have the attention and following that it does. However, it did nothing for me. I could only stomach five pages of this horrible beatnik science fiction garbage at a time. I still can't believe I didn't give up on this book. I think if I would have read it nowadays, I would have tossed the book out after fifteen or twenty pages, right next to The Cipher and Unhallowed Ground (the one by Gillian White, not the one that was just released and out on newsstands, which I haven't read).
If you're a fan of Leiber, more power to you. I just can't give this a passing grade.