I think if you're complaining because one game got 93 and another got 94 then you probably have too much time on your hands :P
Anyway, if you read the reviews instead of just having the combination of 34 * approx 1000 words sumarised into a single number, you will see that the main complaints with the game are
Short single player (6 hours is how long they said it took to finish it)
"paper thin plot"
Very little innovation from previous Halo games
Now, this is why reviews include words as well as a big ol' number. Obviously, if you care not for long lasting single player, or are buying the game mostly for multiplayer anyway, and especially if you really loved Halo and don't want them to wreck the series by moving too far from its roots, then obviously the 80 isn't going to be aimed at you.
Edit - fixed a typo