The only thing I wish to mention here is the Portal 2 release. On steam you could buy the game for 45 euro pre-order (normal price 50 euro). On the day the game finally came out, my local retailer was selling the game for 33 euro. And it's not just Portal 2. Lot of times the games are cheaper in store than on Steam.
Steam is overpriced. They are cutting away 'the middle man' and you get nothing in return except 24/7 availability. These deals on Steam are at least a step in the right direction. But overall I'm not yet satisfied with how Steam handles things.