As noted in a previous post, I've been having a blast with the just-released 1940 census. I did not use Ancestry.com's census site as much as I had hoped, as the locations they chose to upload first were not the ones I was, at the time, looking for. (Their census maps were invaluable, however.) Initially I had to depend on the National Archives' site, which was more than a little frustrating, as they had seriously underestimated how high demand would be, and the system crashed early in the day. By the next day it was up, but slow. Still, I didn't mind too much clicking "next page" and then doing something else for a while. What was most exasperating was the inability to choose to go to a specific page number without going through the agonizing "next, next, next" process.
I found Steve Morse's site more useful than the NARA's site itself, even though he links to the NARA images. Don't ask me how he did it, but I got a much faster (though still slow) response time for the NARA images through his site than directly from theirs.
Easiest of all to investigate were my Florida relatives, as Florida was one of the first states uploade by FamilySearch. They, at least, know the value of the ability to "go to page 5"! Their save image function worked better than the NARA's did in the early days, also.
The great news is that Ancestry.com says it will have every image online by no later than 2 p.m. tomorrow (Friday). Remember, the 1940 census is free on Ancestry for all of 2012, and much more of Ancestry's impressive content is free until April 10. FamilySearch is always free.
Ancestry's YouTube channel has a number of videos that might be helpful for someone who wants to dive into this.
As for me, I plan to investigate the Ancestry site once the database is complete, but basically I'll have to wait until the images have been indexed to do much more. I found all eight of our grandparents and their families, plus a few others who were nearby, because I already knew where they were living in 1940. For those whose location I'm trying to discover, it makes no sense to spend hours and hours pouring over census images when merely waiting will make the job so much easier. I'll admit it's fun, though!