I have to say I personally like achievements. Only, however, when they are meaningful. Not for example 'Meet the Hunter' in HL2: EP2 which is basically just an achievement awarded for continuing in the story. You haven't had to do anything extraordinary to achieve that, you've just progressed as the story intended. It feels somewhat hollow.

Sticking with HL2: EP2 as an example, the achievement 'Rocket Man' where you need to take the gnome from the start for quite a significant distance is a far more rewarding achievement, because not only have you had to play the game, but you've had to carry round some peripheral object with you and ensure that it doesn't get lost along the way.

With the harder achievements also comes extended replay value, to make sure that when you play the game through the next time you do something that you didn't do previously, which you may have missed or have been unable to do.

Multiplayer game achievements like Call of Duty 4's challenges, and the bonuses you get for 3, 5 and 7 kill streaks (UAV, Airstrike and Helicopter respectively) are extremely vitalizing. They give you an incentive to try different things, to alternate tactics and weapons.

Achievements are great...they just need to make me feel like I've landed on Free Parking, rather than having collected £200 for passing Go.