I got my EOS 3 a few weeks ago, i've already run a roll of expired film through it, and half a roll of Tmax 400.
It takes all EF lenses (not EF-s of course), full autofocus and everything.
45pt AF, with f/8 focussing in the middle (it works with my 70-300L and Kenko 1.4x, sometimes it misses because the AF speed is the same as without the TC, but that's the Kenko's fault, not the camera).
AF-Spot-linked metering (for 11-points) also isn't available anywhere else but the 1-series.
I got it instead of the 1V basically because of the eye-control Focus, and they go for $200 or less, a 1V can be $4-500. Otherwise there's not much difference between them, the 1V is better sealed (no idea how much though) and has higher fps (I always shoot high-speed on my 7D, but single-shot on my 3, no wasting film).
Mine cost me 91GBP + 27 shipping, from a real shop in the UK offering warranty and all, via ebay (i just checked, they don't have any others listed or i'd have linked them).
Also, I've got an Ed-Mika'd FL 55/1.2, aparently the rear element hits the mirror of 5D etc, but it's perfectly fine on my 3 (as it is for 1-series, something about thinner mirror-mounts)
In short, it's the only EOS 1/1D/1Ds series camera to not have a '1' in its name...