I hadn't intended to post much more about this since I was already certain prior to its release that the Doom 3 BFG Edition would be little more than Zenimax/Bethsoft/id Software simply trying to re-sell to me something that I already have, but now that I've actually had some hands-on experience with the release I feel compelled to post a word of warning.
First and foremost: don't be fooled by all the hype about the "remastered graphics". For the most part these simply consist of hacks or tweaks that modify the lighting. They do make the game look a bit brighter and sharper, but the same effects can be accomplished with the original game through some configuration tweaking or even console commands. If these are remastered graphics, then I've been remastering games myself for almost as long as I've owned a PC. There are some changes to the menus that look nice, but they aren't worth buying a new version of the game for.
Which reminds me: there's no menu option available to easily access mods. Unless they can be activated through console commands, you'll likely have to forget about playing any of your favorite old Doom 3 mods with this version.
The gameplay has obviously been cheapened for the benefit of the console gamers. There's more ammo and health packs laying around and I've noticed a monster or two being absent from where I remember them being in the original. Playing the game on the "Marine" difficulty, I'm in the fourth section of the Alpha Labs already and the only times that I've died were because I fell off bridges. The changes they've made to the flashlight (being able to hold it and a weapon simultaneously) are nice enough, but since the lighting is now brighter in most areas the thing is almost superfluous.
In my opinion, the only redeeming qualities this version of the game has are the new Doom 3 levels (I think there are eight of them, but I haven't even given them a try yet) and the fact that it includes a NO REST FOR THE WICKED .wad file, at last making the Doom 2 add-on available to we PC gamers without needing to pirate it. Are these things worth $30 USD ($20 if you already have the STEAM version of the original)? If you're the sort of Doomer who needs to own every Doom thing ever made, then it's probably worth your while. If you're a gamer on a budget, then I'd suggest waiting for it to hit the bargain shelf in a few months.