I rarely enter these kinds of discussions with new games, BUT I'd have to say "Diablo III". It's not a bad game, but it's not a good one either, it's very much the definition of "Mediocre". I mean it does what it set out to do, I run around, click on monsters, they fall down and I pick up treasure, sometimes a harder monster makes me sidestep it's attacks. I can customize my character but only within very specific parameters, and they are the same ones as every other character of that type. None of the skills are paticularly new or exciting, nothing I haven't seen before. The game looks good, but with current technology I expect it to look better than the games that came out a few years ago, so that's pretty much expected, the basic monster models convey menace, but don't have any paticular personality or art direction that makes me feel they are anything special... just passable fantasy monsters like in every fantasy game.
There is nothing wrong with Diablo 3, but nothing exceptional about it either. I'm not knocking it per se, I can't say it sucks, just that it doesn't excite me.
Of course I admit part of it is that there are older games that I think did it better. I keep mentioning this little known gem called "Sacred 2" which I think got overlooked due to people waiting for Diablo 3 and it not having the same brand name. Technologically speaking it's not as good as D3 being both older, and also being buggier due to what I sadly have to say is a less skilled team. But what it had was personality, instead of one hub you visited, you had an open world and multiple towns with quests in them, you could choose to worship differant deities which have you special abillities (like summoning a ginormous demon), you could ride mounts, and while not unique you had skill trees complicated enough where you could build some really cool characters. Where in D3 there is really only one way to play a specific character who has very set builds, you could say take a basically ranged character in Sacred 2 and turn it into a melee monster, such as making a Dryad based around riding a giant monitor lizard and bashing everything to death with dual wielded staves (the Dryad/Wood Elf is by default an archer type character with some nature based druidic magic stuff). One of the Sacred 2 characters was a cyborg (which was justified by the game's lore, even if the story was minimal at best) with an egyptian theme right out of Stargate, that could blast things with all kinds of tech based powers in an otherwise fantasy setting (and honestly had a perfectly good reason for being there and doing this, albiet these guys are very rare and it's a unique set of circumstances having him run around).
See, that's what Diablo 3 lacks... personality. It's dark "halloween town" atmosphere just doesn't cut it, I mean it's good, it does the job, but it's nothing more. It's like a fast food cheeseburger, it's tasty, it gets the job done, but it's not something that your going to say "wow, this is great" about. It fills the need when there aren't other options. Diablo 3 is mediocrity personified, and I really can't say that I remember playing a game that was just so bloody average in every respect, even games that I say are "meh" tend to be weighted one way or another, but Diablo 3 is incapable of motivating me to either love or hate.