FO3 worked piss easy for me on steam with all the DLC, had no issues getting them to work. just had to enable them once in the launcher.
Allow me to elaborate.
Play the game vanilla, with just the Steam updates, and the game sucks. Crashing, bugs everywhere, and more defects than a room full of thalidomide babies. I wanted to test whether my memories were accurate, or if they were tinted. After the dozenth crash, being ejected into the air (Skyrim Mammoth style) when a grenade bouquet hit me (and dying from the fall), and more poor textures and non-loading ones than I could count I determined my memory was very rosy. The
only reason that Fallout 3 was remembered was because the mod community fixed the steaming pile of turds that vanilla Fallout 3 was/is. I thought 7+ patches would have fixed it, but it definitely didn't.
As far as getting the new content to work, my game was being difficult. Apparently load order is insanely important with the DLC, and the default configuration...was less than ideal. After going to the Nexus, downloading the community patch, reading up on the ideal load order (to be clear, this was the .esms for the DLC and no other mods), restructuring it that way, and booting the game through FOMM all of the DLC suddenly worked. I logged in, and a stream of updates came through.
Allow me to frame this as progress, that means Fallout 4 might only be a gimp, and not a stillbirth that the community needs to nurture into a good game.
1) Fallout 3 blows. The community patched the crap out of it, and it's relatively good, if still buggy, in its current state.
2) Fallout: New Vegas was buggy, but took way less community effort to fix.
3) Skyrim was a bug fiesta for months after release. The big change here is Bethesda actually put a lot of effort into quashing bugs. They fell through on some elements (that UI is horrifying with a mouse and keyboard), but the community polished that golden turd trophy to a mirror shine. Yeah it might be a turd, but I wouldn't be opposed to having a chunk of gold in that shape.
4) Logically, Fallout 4 should release with minor bugs. If the established trend is followed, we're looking at something that is actually playable, and the bugs should be pretty minor. The community will take that solid gold heart, and build it the monstrous skeleton which will give it life, rather than simply having to deliver life support to keep the thing working.
Point 4 is conjecture, but it'd be nice. If Fallout 4 releases like Fallout 3 I won't be buying it until 2017. By then you should be able to get the GOTY cheaply, and the community will have fixed everything backwards that Bethesda couldn't be bothered to fix.