Got the trial version, tried it out for that week, and decided it was worth the plunge. It beats Everquest as far as 'realism' and movement (doesn't take 1/2 hour to cross the world). WoW is nice, but I like DDO for the more original D&D take on the adventuring and system.
The graphics can be unearthly beautiful, but running around in an adventure with them on super-high will slow any system down. I run at the 'medium' setting, and I have a 3200 P4 w/ 1G ram and a 64 nVidia graphics card.
Plus the game can only get better as they go along... adding more levels, classes & adventures.