The last game I preordered was Age of Conan. At least that's the last game I remember preordering.
I haven't done so since, not because of any issues with preordering games, or the games themselves but simply because I haven't felt the need to do so. Although I have felt a tinge of jealousy from time to time with players getting into the head start periods just before a game officially opens to the masses. Especially when I read blog posts from other bloggers who are all having a fine old time.
I guess the other factor holding me back from the preorder purchase is the old adage never play on launch (or patch) day. That was strongly reinforced with the recent Simcity debacle, but has been a part of playing MMORPGs since the early days. That initial influx of tens of thousands of players hitting the servers for the first time really tests how well a developer has put together their code. While recent years that has got better, memories remain of disastrous launches that finally settled down after some weeks or months.
At one time I figured that since MMO development was a really new field, that developers would eventually develop the tools and knowledge to ensure smooth launches, and for the most part I think they have, even if one of those tools is putting players in massive queues. But game software network development on large scales is still somewhat inexact, and the bigger companies capable of developing and marketing AAA games appear to want the best of both worlds: low initial spending on server hardware, but still grabbing as many players as they can as early as they can.
It all boils down to the fact that you can't be guaranteed a bug-free gaming session, or even getting past the queue, on launch day.
How about you, do you preorder, or do you prefer to wait?