It's a great idea as it does extend the replay value but I do think it isn't being used to its fullest potential. Achievements are sometimes pathetic, outrageous, unrepresentative scores, etc. They give a base system for all of this with no filler on the inside haha. And the requirement for all games furthers how bad it can sometimes be.
I like the idea, but I think it needs more refinement on execution. Not necessarily MS's fault either, but it would be nice to know that there is some actual thought put into some of the achievements. So I guess more of a fault of some developers but I'm sure MS could lend a helping hand eh. We all like to extend replay value and feel accomplished, but just like any game, that accomplishment and replay value needs to actually be worthwhile.
