I lost interest in the Forgotten Realms somewhere around 10 years ago, but I'd been a big fan of it before that. When I started hearing some intriguing things about the new 4E Realms, it piqued my interest again, and I figured I'd buy the new setting. Even though I actually have no plans at all to run a game in the Realms, I still bought it, just because it looked cool.
It's a neat book. I like it. Probably very little in there that I, as a non FR-DM, will ever use strictly speaking, but that's okay. It's still a nice book to have in the 4th Edition collection.
The surprising thing for me is, actually, that the Realms are changed a lot less than I was expecting, after reading an article or two and listening to a few podcasts about the topic in the preceding months. I really thought the world would be considerably more torn up and jumbled than it appears to be. In short, it's not nearly as "points of light" as I was expecting, and certainly not as "points of light" as the generic assumed setting for 4E seems to be.
Yeah, there are big, significant changes, on a lot of levels, but civilization seems to be going on pretty much business as usual, really. It's not nearly as Fallout or Earthdawn as I kinda hoped it would be. I was thinking that the whole Spellplague and assorted debacles of the timeline shift would be more like an apocalypse, really reaving the whole world to its core. But my impression from the new campaign guide is that, at least for the majority of the most civilized/powerful demographics of Faerun, it's a lot closer to, "Well, that was annoying! Most unpleasant, indeed. Someone should clean that up, I say. Anyway, let's go see what's on sale at Aurora's Emporium today, shall we?"
But all in all, it's cool. If I was interested in using any pre-written setting, I'd definitely come back to give the Realms another spin now. It's not so different that you won't recognize it, but it's different enough to be new and interesting again. I think they did a good job.