Djinn sent me an e-mail with an interesting thought: Buying a game on Steam is the equivalent of a bind-on-pickup item in a MMORPG. Unlike a game you buy in a box with a disc, a Steam game can not be traded second-hand, it is "soulbound" to your account.
For the price-sensitive, Steam is not a good deal, especially over here in Europe. Steam fixed most games at an exchange rate of 1 Euro = 1 Dollar, so depending on the real exchange rate Europeans pay between one third and one half MORE than US players for exactly the same game and service. Also Steam games in many cases cost the same as the boxed version, so given that a game which you can't resell is obviously worth less than the same game which you can resell, Steam games are overpriced.
Fortunately for Steam I'm not very price sensitive. And I recognize the potential to save some money with Steam: By waiting. In the era where games only came in boxes from stores, finding last year's game was often difficult, so I had a tendency to buy games when they came out, and then keep them unopened in the shelf without playing them. That became significantly worse when I started playing MMORPGs, which tend to eat up a lot of time, so now I have an impressive collection of unplayed games waiting for the next WoW break. So nowadays I don't buy new games any more, unless I want to play them right now. Buying them when I feel like playing them not only saves me from buying games I never end up playing. Quite often Steam sells you last year's games at a considerable discount too. And for games you are sure you will play, you can always look out whether they appear in some weekend deal for half price.
So Steam and similar services have both good and bad sides. In the end everybody needs to judge how important it is for him to be able to sell his games second-hand. Is the added value of convenience enough to balance the effectively higher price for soulbound games? You decide!