Fallout 3 has in common with Obilvion: They both have open sandbox 'go anywhere' gameplay. They are both first person. They are both RPGs. Thats it.
Actually that's not it - they're made by the same developer, and are based off the same engine.
Seems like there are two styles of answer in this thread; firstly, cliches uttered by other gamers, this appears to be what the OP was aiming at for this thread. Personally, I get a bit annoyed by the following cliches:
"Graphics don't matter, gameplay is King"
--Yes, but what's wrong with wanting great gameplay AND great visuals?
"It's not realistic"
--Yes, that's because it's a freaking COMPUTER GAME! The vast majority of so-called 'realistic' games are easy to pick holes in anyway.
"<Game X> runs smooth as butter maxed out on my <card Y>, it only slows down on <level Z> when there's a massive firefight"
--Well, it's obviously NOT 'smooth as butter' then is it, if you are getting slowdown
"Doom 3 is too dark"
--It's supposed to be dark. That's why they give you a flashlight and the game has brightness and gamma commands. I had far more trouble with the level of darkness in HL2 than D3, because it doesn't let you tweak it far enough.
"The human eye can't see more than 30/60/xyz fps"
--I've yet to see any concrete upper limit to what kind of framerate some people can detect, but it's certainly well in excess of 100fps
"This is an absolute disgrace, I spent £99999999 on my uberl33t gaming rig and this new game won't run maxed out"
--Note the obsession people have with "MAX settings", rather than what the game actually looks like. If you relabelled "Medium" to "Ultra High" in some games (e.g. Crysis) and deleted the top-end settings, people would probably feel much happier. What the sliders in the options menu say is not the only way you should be judging how good a game looks and performance.
"PC gaming is dying"
--Actually, this has become so much of a cliche now that even when people put up a reasonable argument for it, people just ignore it out of hand. Either way, it's probably one of the purest cliches around, in that it's been going on for the past 10 years or more.
"This game is the buggiest piece of **** I've ever played, didn't they do ANY testing at all, the whole QA department should be sacked!"
--Actually, they probably did a lot of testing. One of the fundamentals of software testing is that you can never expect to detect all the faults. At the end of the day, most games which come out around holiday season will likely have been rushed out by the publisher to boost sales.
"MMORPGs (WoW in particular) are for sad losers with no life"
--Well, the fact is they are arguably one of the most popular game types around. The weird people are the ones playing other games

(bear in mind I've never played a MMORPG, so I'm not 'defending myself' or anything)
"EA sux0rz / Oh noes, this game is doomed now EA have got hold of it"
--Yeah, we've got the message. EA aren't popular. Get over it.
As for the other type of cliche - design tactics that we've seen a hundred times before - here's some of my choices:
--Midway through the game, you get captured (or whatever) and all your weapons and ammo get stolen. So those 100 rockets you've been saving up for a rainy day / boss fight are cruely taken away. The ONLY time I find this acceptable is when you get back exactly what you had before after escaping, I seem to remember Deus Ex (?) did this. It's just really annoying that you don't benefit from being frugal with ammo, meanwhile players who have rampaged through the game using up all their best gear aren't at a disavantage becuase of that armory conveniently positioned right outside the prison block.
--Getting betrayed by a character who helped you earlier in the game in terms of giving you advice and telling you where to go... it's such a cliche that you almost come to expect it now. In some cases it isn't even really explained that well, in terms of why they were helping you to start with. Not going to risk any spoilers by naming specific games, as I'm sure you can all think of some.
--RTS games where capturing an objective triggers a scripted enemy assault from forces that suddenly materialise out of nowhere, despite you having meticulously cleared the playing area beforehand.
--Respawning enemies. Just FOAD.
--AI controlled cars that are running on tracks, never deviating far from the racing line and seemingly immune to being clipped on the rear side.
--Enemies always having the same amount of health / weapons always doing the same amount of damage. Basically what this means is that after a while, you learn precisely the most efficient way of killing each type of enemy, because they will ALWAYS die if you hit them with that. Games should make better use of randomised health/damage.
--Bosses which can ONLY be defeated by the use of some weird gimmick, often involving running around flicking switches to trigger some kind of machinery. I hate that, which makes proper boss fights where you can just let rip with your BFG/RL and pump them full of lead to bring them down all the more satisfying. Gimme a Doom2 Cyberdemon over the Doom3 one any day!