I think that the achievement system is really good and it doesn't put me off whilst I am playing.

Some games are better than others in the way they deal with achievements, Bioshock is probably one of the better games for this. I love the Irony achievement which I found by chance but when it popped up on my screen my first reaction was 'cool!'.

If it means that I play a game for that bit longer or do a bit more exploring than I normally would then it's all good!