I adore FR, and when I used to run D&D based games, used it for a setting. So long as it's 2nd ed. or earlier.
The 1st ed. FR products I own are the Grey Box set, Undermountain set, and all the FR 1 thru 13(?) source books(well, I've given most of these away actually). The 2nd ed. stuff I own is Aurora's Whole Realms Catalog, a Volo's Guide (can't recall which), Maztica boxed set, Undermountain II boxed set, the Atlas, the Hardbacked campaign book, Pirates of the Sea of Fallen Stars and Evermeet sourcebooks. The only 3e stuff I own is the FRCS, I had The Unapproachable East but gave it away to friend.
That's alot of stuff now that I stop and look at it.
The 1st edition stuff was the best, a lot of fluffy material with some crunch and plenty of room for customization by a DM. A lot of the FR series source books we're released after 2nd ed. was out, but the source books in general (IMO) had more of a 1st ed. feel.
I personally noticed a big difference between 1st and 2nd ed FR products just by the physical appearances alone, let alone the by the writing styles.
It was the 2nd ed. products that seemed (IMO) to mark a decline in the FR product line, more crunch less fluff. I attribute this to the writers of the 2nd ed. material (or the bulk of it) as having less of an Ed Greenwood influence than writers of the earlier materials. That would be, Ed is consulted but never had written out or expanded on some of the topics now being written about. Plus the writers also had a larger influence from the FR Novels to include, which weren't as numerous when some of the earlier material was written.
3rd ed. and beyond, from what I've seen has just ruined the setting. Still plenty of fluff, especially with some of the timelines. But there's just too much crunch and too many details to suit my style of play. For example, 3rd ed. gives more information on the Imaskari and the creation of Raurin, and gives the crunchy numbers to go make it playable under the current rules w/out detailing every little aspect. Then there is the Champions of Ruins book which seems to me to nothing more than a specialised "Realms feel" Book of Vile Darkness.
So for me FR has become a slowly declining product with each successive edition release of the D&D game. At the start a good Homebrew setting with just enough detail to make it customizable and enjoyable for other DM's/players only to become the bastard splat-book setting dump for WoTC's/Hasbro's 3 and 3.x product line.