Okay, so Amazing Spider-Man issues 509-514 came out a while ago (*ahem* six years), but I just picked it up in trade format on sale last week, and finished it last night.
There is a very good review of the story here, and I agree with most of what the author says, except for the need to have this properly retconned out of the plot.
I think that it was a poor follow-up to the more interesting run dealing with Spider-Man's link to the spiritual world and while Mike Deodato's art was pretty to look at, that no fan really wanted him to draw a panel of Gwen Stacy in the throes of passion with Norman Osborn. Seriously, it was kind of gross.
I don't really get what the goal of this story was, from J. Michael Straczynski's point of view. I thought that it killed a lot of momentum that his book had going following the conclusion of the Ezekiel story. And killed it in such a weird way, by making Gwen the girl in high school who gave it up to one of her closest friends' father.
If they never have another plot line centered around Gwen Stacy again, I'd be happy.