This is quite comical, anyone that has given this game a high score clearly hasn't played it. I would have to say something more like 6/10. I think a 40% hit due to playability is a good decrease.
the game is a game of 9/10 or 9,5/10..... BUT WITHOUT BUGS.....
the bugs (the one that cause near the 50% of the gamers to STOP PLAYING praying for a patch) decrease the vote on the game to 6/10 or also a good 4/10 (if you cannot play it it is not good)
a lot of review are done on release candidate versions of the game and the reviewers are sure that for the release date all mayor bugs will be resolved.
BUT FALLOUT NV is a new experiment you can call it VAULT 121 experiment :
- give a game, a potentially very good game to a group of people.
- close them in a vault
- the game after near 10 hours of game start to be bugged but so bugged that you cannot go on.......
- no patch are available because the game was done by some modders and not by real programmers.
- see how many time will pass before every people closed in the vault will go mad and start killing every one!