I've just bought a pristine, though used, 1D3 about two weeks ago, which replaces my 1D2n that I used for over a year prior. What can I say? WOW! The body feels like a 1D and for those of you that never held one and are really into your bird photography, ONLY hold one if you can afford it. Though the second hand market is now flooded with very good quality bodies and they are as good as the day they were released. I love having people around who always have to have the latest and greatest, which means that predecessors of the current 1D line-up are becoming cheaper and cheaper. The fact they are "outdated" because of improved technology does NOT mean they are garbage. If I recall a few years ago everyone had 1D3 bodies and were making great photos with them. Nothing changed today. You can put the best technology in the wrong hands and get zilch. Yes, that is how the cookie crumbles. I will never pay the ridiculous prices to buy a new 1D series body.
Rant aside, it's fantastic. AF works perfect (the serial number is outside the range that had possible sub-mirror problems). It makes clean, contrasty and beautiful images, which need very minimal post processing, which is what I LOVE!
The 10fps is handy for fast action, but it's annoying as the shutter button is quite sensitive so even if I want to take a single shot while in high-speed mode, I can accidentally fire off two or three. I think in a few more sessions that will be sorted out as I develop a better feel for the shutter release.
ISO1600 is excellent and clean if I expose properly (shoot to the right) and even ISO3200 is relatively OK for me, though more experimentation is needed at the high-range ISOs.
You can really grab a bargain of a camera now that there are 1D4 and 1Dx out there that every one seems to be snapping up.
Again, like I said, having the latest of anything does not make for a better photographer.