Found a few spare hours to watch You Only Live Twice last night. It continues the gradual decline in quality since FRwL - I score it a 6.
It's the first film where I felt it dragged a little. Blofeld is disappointing as a villain - a bit too feeble to be head of SPECTRE, and I never get the impression he poses much of a threat. There's no spiky dialogue with Bond either - I don't think the script was that great in general. And that shot of the volcano after the explosion... awful.
All that considered, I still thought it was fairly watchable with some enjoyable scenes. There are some nice locations and shots (eg the scene on the harbour rooftops) and the theme song is good too (although the melody makes me think of Robbie Williams' "Millennium", which is where I first heard it).