Ben Kuchera of Ars Technica lays out the one major reason why the casual gamer—the guy who plays only once every few weeks for a half hour at a time—would prefer the Xbox over the PS3. Firmware. Updates.
There are a couple compounding issues here, but they can all be lumped into the update/download scheme that Sony's set up for the PS3.
First, you've got regular system updates that add minor features every few weeks, instead of the major system updates (at most) twice a year that Microsoft does. Even with the major updates, Microsoft manages to push them out so both the download and the update process is fast. Not so with the PS3, which leads to the second point Kuchera makes.
The other problem is the download speed. By Kuchera's tests, you're only getting 2.5Mbps, which is on the low-end of DSL speeds. These slow downloads, combined with the constant updates on the system level as well as the individual game level (which are fast on the Xbox 360), treat you to a 30 to 60 minute download-and-install wait every time you want to play a game.
But, ho! Sony has found a solution: PlayStation Plus. For $50 a year, you get these firmware updates and game patches pushed to you, instead of you having to sit through the wait every time you want to play a game.
A real fix would have to come in two parts: less frequent mandatory system updates that don't add significantly new features, and much, much faster pipes to deliver updates through. [Ars Technica]