CoD4 has good achievements because they're very challenging but still attainable for almost anyone, and simply require player skill. Going through War Room or the epilogue on Veteran is hard, sure, but those are perfectly doable achievements.
There are two types of achievements that Microsoft should simply ban.
1. Unreasonable achievements. Achievements that are so ridiculously difficult that you can't reasonably expect anyone to get them. Sure, some crazy people will always get them, but achievements are not supposed to be meant exclusively for people insane enough to level up 18 classes to level 75 in Final Fantasy XI. Getting to the top of the world leader board in GRAW is a modest achievement by comparison.
2. Meta-achievements. Achievements that don't really have anything to do with the game. Team Fortress 2 requires you to play a game with seven people from your friends list, but what does that have to do with the game? I don't have anybody on my friends list, on Steam or Live, so Valve is expecting me to go out and recruit seven people and play a game with them? For what? Why? What the fuck? This is a completely extracurricular achievement that's conducted almost entirely outside the game. What's next, standing on your head in front of the Live Vision camera while touching yourself? OH, WAIT: Rainbow Six Vegas requires a Live Vision camera for taking a picture of yourself, and this peripheral is of course not otherwise used by the game in any way. Yes, Ubisoft, I'm totally going to go out and spend 40-50 euros on a fucking useless peripheral just so I can unlock one achievement in a game. I guess the next logical step is to just directly charge players money for unlocking achievements.
Microsoft should seriously excercise some quality control instead of letting shitbag developers get away with achievements that by any reasonable standard are broken. I was really excited about the achievement system before I got my 360, but I eventually became disillusioned and now I couldn't care less.