We've done it several times - they have the traditional blue/dark screen for more formal poses or they can do the "green screen" technology to make it appear as if you're on Main Street, in front of a Christmas tree, etc. I've never waited more than a few minutes, but also tend to hit DS during the day, not evenings or weekends. When we asked about reservations (trying to do a family pic with military sons home over Christmas break) they told us they didn't. Worst case if a long line, one person could wait in line while the others shop nearby.