A game's guality is really dependent on the quality of its achievements.
The Game with the most boring achievements was Oblivion for the 360. You just have to complete the main quest and some guild quests. bethesda did a much better job with Fallout 3.
One of the best achievements ev0r is the "wax on" achievement in Geometry Wars 2.
"Wax off" wasn't that good, because it was just a harder (much harder, still trying it

) version of wax on. Stackable achievements are really pointless. Why do I need a "win 5 races achievement" if i have to do it anyway in order to do the "win 15 races" Achievement?
It's sad, that achievements are cut from the PC versions of many games. I was a PC fanboy for many years, but i recently got a 360 because some games are just better on the 360 with LIVE and achievements. For example, i bought Race Driver:GRID again for the 360 because the 360 version has a really grat achievement mix tat requires the player to do things he wouldn't do normally (e.g. "do a 360° turn with your car and still win the race"). I think i played the 360 version more than the PC version. Even if the gfx etc. are slightly worse.
Some, atmosphereic story games (like Mirror's Edge or Dead Space)don't really need achievements, but I can't imagine playing Resident Evil 5 without achievements and it would be best for capcom not to remove them for the PC version for no reason. Without achievements i would have played through the game once in co-op on medium difficulty, and now, We completed it on Veteran, then we made another run to collect everything, then we got "S"-ratings for all the levels and we're still not through yet, because we have to play it a 4th time on the highest difficulty setting (pro mode) in order to unlock all achievements. RE5 also has some funny achievements for here and there like killing an enemy with a rotten egg. Really love achievements!
What I don't like are cheap pseudo-achievements that cannot be seen by the riends online. Why should I make medal XY in game YZ if nobody will see and appreciate it? for example, the PC port of Assault heroes still has some sort of achievements but they're pointless, because nobody will see them except the ppl who did them.
yes, bragging is just the point of achievements.
By the way, there's something much worse than bad achievements: bugged achievements and achievements that don't work anymore. For example, as far a sI know, there are some LIVE games with multiplayer achievements that cannot be obtained anymore because of server changes or shutdowns.
I also hated it to play through half Gears of War on Insane difficulty three times, because everytime the game froze and deleted my savegames so that i had to start again.
The last time i tried it, a friend has hosted the game whose savegame didn't get deleted and I was able to play through the final two chapters on Insane. It's just bad that I still don't have the achievements for playing the Whole game on Insane because the game doesn't know that I played the other three chapters before.
so please, developers, If you aren't sure if everybody is able to unlock the achievements and cannot ensure a unbugged game where it is possible to actually finish the game, just don't add achievements that require the players to do the impossible. hard achievements are ok, but no impossible ones.
Achievements also shouldn't be inflated. A mid-quality XBLA game doesn't need achievements that require the player to play the same mode for 200 hours. They should fit the game and all the achievements should be finished just when the game gets boring. Not when the main storyline or whatever is completed but when the player has seen everything in the game. It's pointless to ask the player to do things over and over again the same way.
The need to play Resident Evil 5 at least four times is ok, because you'll always get new weapons, constumes and upgrades.