I just got a D70 a couple of days ago and took it out for its first round of pictures today (rain had prevented me from getting out earlier). For the kind of photography many here do, it is an interesting little machine to think about. First of all, its image quality is RIGHT in there with the rest of the 6MP crowd (as Michael says, they're pretty much bunched together now, anyway). Second, it is (to me, anyway) a nicer camera to shoot with than the Canon D30/D60/10D. This is simply because of feel and the way I take pictures.
My two best examples of this are the depth of field preview and the AF Area selector. On a Canon, the preview is on the LEFT side of the camera-not a very useful spot if the lens is resting on your left arm. Admittedly, I have a nonfunctional left hand, so I don't cradle lenses in it-perhaps the Canon preview button is reachable if you're holding the camera that way.Even so, would you really cradle a longish lens close enough to the body to reach that preview button anyway? While trying for the DOF preview on the Canon, be sure to miss the nearby lens release (a control that should be kept well separated from all other buttons to prevent accidents!) Nikon has wisely placed the DOF preview on the bottom RIGHT of the lens mount, in easy reach of my right third finger.
The AF area selector is the four way pad inherited from the F5 (and many other Nikons), not used for any other control in shooting mode. It doubles as the menu navigator, but that is never confusing. Canon uses the rear control wheel, which has two disadvantages. First, it only gives one axis of control-much harder to pick a point with-you have to scroll through all of them. Second, it is also the shutter speed control, which reduces the convenience of AF point selection. EVERYBODY else has copied Nikon's control layout since the F5, why can't Canon?
Metering and focusing seem good (it's the first day with the new camera, though). Both are much better than the D30 I used for years (I'm a longtime D30 user, also somewhat familiar with the 10D). Nikon says that the D70 uses their famous Color Matrix meter-if that's true, this little camera's going to be hard to fool! For those really bizarre situations, there's spotmetering (nice tight pattern, and linked to the AF point.
Nikon is supporting the D70 with a good selection of high-quality DX lenses that give us true wide-angle on a digital body, as well as a wide range of Nikkors carried over from the film world. The lens range is nice, although I wish for more VR AF-S (Canon calles this combination IS USM) lenses at affordable prices. Canon certainly does better with long lenses. The included 18-70 AF-S DX is a nice little lens with a very useful focal length range on a digital body. I'm looking for a good long lens to go with my D70 (something that goes out to at least 300, maybe even 400).
In addition to the lenses, Nikon has a lovely flash system with this camera. The on-camera flash uses Nikon's sophisticated iTTL control, and actually tends to get exposures right (which I can't say for the D30). The (expensive) accessory SB800 flash is amazing-very powerful, gets the exposure right, easily settable flash compensation for fill flash, and wireless capable (without owning two of them because the on-camera flashlet can serve as the controller!) My only complaint about the flash system is that switching the on-camera flash between being a flash and a wireless controller is buried in a menu. That should be on some button. Of course, no other camera short of a Hasselblad H1 (which I believe has a built-in PocketWizard or something) has a built-in wireless flash controller at all. The wireless capability is going to be really nice for the occasional fill-flashed nature shot, and amazing for the event photography I do on the side.
The D70 is a very nice little camera, one that many traveling photographers should pay extra attention to due to its size and weight, but it isn't perfect. Its build quality reminds me of my old D30 in most respects (well-built, but clearly plastic). 10D's I've shot with are better than that. The Nikon Capture software is slow and annoying (although very flexible) on my 1 gHz PowerBook. Canon's RAW converter is no better, but you don't need it because all the Canons are supported by Photoshop's built-in Raw converter and Capture One. Right now, nothing but Nikon Capture supports D70 RAW files, although Adobe, Bibble Labs and Capture One are all headed that way as quickly as they can go.
Nikon has the gall to charge for Nikon Capture, even in its slow, annoying state, and there are a few camera features you can't access without it (tone curve downoad to camera), even once one of the better RAW converters is released. Of course, to get a downloadable tone curve on a Canon, you aren't looking at a $99 piece of software, but a $4,499 EOS 1D Mk II!
My other complaint is that there are one or two places where the D70 seems less well built than even the older Canons (let alone the 10D and whole 1D series). The major one is the battery retention mechanism. The D30 used a little spring-loaded "foot", while the D70 relies simply on pressure from the door and the terminal springs. We'll see how it holds up, but that foot was nice extra security (as well as making the battery easier to remove on purpose. Overall, though, the build quality is like an upper end consumer SLR, just as the D30 was, and a big step up from any Rebel, digital or otherwise!
Overall, a nice DSLR in a light, affordable package with almost no missing features and a few great ones for a good price. Right now, my pick of the lower-end market (up to the 10D and D100, but not counting the big pro cameras).
-dan