Due to Blizzard needing to log players into their servers, users may experience delays when trying to play the game at launch. Early adopters may suffer timeout errors following waits of up to forty seconds. That'll be fun.
"It's possible we'll need to adjust the rate at which we're logging people in to ensure a stable experience, and if we do you may see a delay when attempting to login," Blizzard warned. "Please be aware that a delay of up to 40 seconds is possible while the game attempts to connect you. If your connection doesn't succeed in 40 seconds, you'll be presented with an Error 37 message and asked to try again."
This is a weird issue, since the DRM has been justified as being required to make the real-life auctions work without cheaters. Of course, one could argue the inherent pointlessness of the auctions in the first place, so this is a pretty grey area. Personally, I'm never for DRM that inconveniences the user for the benefit for the publisher, and as much validation as this may have, that's what it boils down to for me, especially given the stunning failure rate of DRM as a method of stopping any determined vagabond.
In any case, we'll see how many users actually get to log in on launch day. Why do I predict a lot of rage incoming on May 15?