Interesting thread, with some interesting arguments, many of which I find myself agreeing with.
Someone said Dr No. I'd respectfully disagree - I think it holds up extremely well as a tense thriller with a dash of sci-fi mixed in. It's very much of its age, but if you divorce it from what we think of as the 'typical Bond film formulae', it becomes a surprisingly entertaining period piece.
That said... I'd like to nominate several 'classic' Bond films as having aged extremely poorly.
In order:
Goldfinger. Yes, I said it. I think it's a solid film with so many random asides and odd story beats thrown into it that it just... drags. There's a game of sodding golf in there, for heaven's sake! Go back and watch it again and I guarantee it's nowhere near as good as you remember.
Thunderball. This film is boring. Long stretches pass where very little happens, all the action is dragged out mercilessly and the underwater fighting completely fails to entertain because not only is it hard to see what's happening but it's all so deathly slow. It's really not held up well at all (except the Bond girl, who remains absolutely stunning to this day).
Diamonds are Forever. Tacky. That's the only word I can think of to adequately describe this film - tacky. It's cheap, unpleasant to look at (check out the casino where Bond meets Plenty O'Toole - ugh!), unbelievably campy and has some of the worst characters in the entire franchise - Tiffany Case does practically NOTHING throughout the entire film except stand around and look pretty. Awful film, I don't know why more people don't think so.
The Man with the Golden Gun. I shall simply direct you to my review of this [http://blip.tv/chrismadisun/madisun-s-arc-26-the-man-with-the-golden-gun-6580089] to fully illustrate why I think this film is so bad. Long story short: it's extremely cheap looking, painfully unfunny to the point of just plain being racist, badly acted (except for Christopher Lee) and has one of the worst car chases I've ever seen.
Moonraker. The concept alone is enough, but it suffers from terrible special effects, a script full of something failing to be comedy and weak performances all round.
Many others don't hold up either, but these are the worst offenders in my book.