bioshock was overhyped perhaps, not overrated.
How was it not overrated?
Bioshock has no fewer than 4 fetch quests, an escort mission, 4 enemy types, sucky gunplay, and the Life o Matic tube thing that totally breaks gameplay balance (yes, I realize you can remove this with a patch).
This is what happened with Bioshock:
Ken Levine: blah blah blah blah blah MISE EN SCENE
Gaming press: omg omg omg omg 
Nobody asked any questions afterwards, like, "Do you think the game is about 5-6 hours longer than it should be?" or "Why do you build up the little sister as some precious creature and then destroy this in the end?" or "Why do you have a ridiculously bad final boss?" or "Did you run out of ideas and thus put in yet another fetch quest?"
I'd give it a high 8.
good argumentation that tells how Bioshit truly is
recently it was unveiled that 2K games refused to allow any coverage of the game to press outlets that wouldn't give it their highest level of prominence possible, and that thus the reviews were some of the "best ones ever"... that explains the ridiculously inflated review scores, they basically cheated
what you don't mention however is that it's ridiculously SCRIPTED, you can't walk for five seconds without having an enemy, an NPC, an in-game cutscene or something in the environment harassing you, it's like LEAVE ME ALONE AND LET ME ENJOY THE ATMOSPHERE, DON'T TRY TO START A FLOWERY CONVERSATION WITH ME AT EVERY 10 SECONDS
I just wanted them all to SHUT THE FUCK UP, how are you supposed to be spooked when there's always someone that tells you what's going on, THANK YOU I'M NOT distinguished mentally-challenged I'M ABLE TO FIGURE OUT ON MY OWN WITHOUT ANNOYING NPCS SAYING IT ALOUD
they really fucked the whole System Shock 2 system so that distinguished mentally-challenged casuals could breeze through it, the regeneration tubes that ruin any feeling of tension are further proof of that
the levels are really small and cramped too, that's another disappointment, it's almost Deux Ex IW levels of bad
6/10 at MOST