Will it be buggy? Yes! It's a Beth game!

Personally, the only "major" problem I had with FO:NV was the first-week "whoops, Steam cloud-syncing destroys your save files" thing. Which was pretty easily fixed (turn off Steam community/go offline) until they ran a bugfix for it.
Other little things, like rubberbanding corpses, CTD's, the crafting menu being a bit sticky.... meh. Just little annoyances (or funnies), not "game breaking".