I don't know, I hear it was filled with bugs.
Well I dunno about it on console since I hate shooters on consoles, and I assume you're getting it for 360, but literally the only minor bug I've found is one single tree floating about a foot too far away from the cliff it was meant to be attached to. Nothing gamebreaking, I haven't had a single crash or anything, playing on PC.
So unless you're going out of your way to make it bug out, you probably won't find any major bugs. Unlike when, say, Oblivion was released (pre-first-hotfix, could not complete tutorial, crashed in less than five minutes guaranteed, rendering engine occasionally shat itself and lagged the game to stuff, etc) or for a less extreme example Fallout 3 (crashed in less than five minutes guaranteed if running on high settings even if your system can handle it) - it's very playable.
As for Fable 3, well, it seems pretty short. If the end of the Road to Rule is the end of the game, I'm about 2/3 of the way through in under four hours of playtime, and I haven't skipped any missions (except co-op ones). I haven't been collecting the collectible stuff though, but really, the first fable was huge in comparison to this. I spent more than 48 hours playing that at my friend's place when it was new and I don't think I even finished the main story stuff.
My honest opinion: Get Fable III, finish it while it's under warranty, then return it and get Noo Vaygus. And make a witty quip if they ask you what problem you had with the game, tell them that the amount of free space on the disc made it read slow or something. If I wasn't lazy and pessimistic I'd probably send a very bitter letter to the developers detailing my disappointment and its causes.
If you want the real "people's opinion" just look at their threads.
Fable III: Nobody has even talked about it. At all. I've seen one person state that it was really short, which I agree with. Aside from that, nothing. Seriously. We waited that long and nobody can find a single thing in the game worth mention except that "it's short".
New Vegas: 35 pages of people talking about the game, discussing characters, freaky semi-game-breaking/unbalanced things. New Vegas feels big both in world size and the amount of content, and that's good, that's how any sort of open game should feel. Fable III just feels tiny in comparison to the first Fable. I hope 360s are backwards compatible so I can play that.