I bought my Nikon D70 just over two years ago. A friend of mine just got a D200 and I borrowed it for the weekend, while we had family in town for my daughter's first birthday party. Here are some thoughts, in no particular order:

- You see lots of discussion about how good the build quality and such of the camera is. Realistically, it doesn't feel all that different from a D70, except for being noticably heavier. The buttons are larger and many things that, on the D70 are buried in the menus, are directly accessible with button-knob combinations. The 5fps shooting is nice. Mirror black-out is noticably shorter. Flash response, particularly in commander mode, is radically better. The screen is huge and brilliant.

- Battery life, as discussed, is crap. On the D70, you can charge the camera and hike off into the wilderness without worrying about it. On the D200, you need to pay attention. This is very sad.

- The D200 is practically a drop-in replacement for the F100 film camera. If you'd been using an F100 as your primary camera and somebody suddenly replaced it with the D200, you'd feel right at home.

- Since I don't have Photoshop CS2, I've been doing the hack of converting Nikon's NEF raw files to DNG files, and then converting those with Photoshop CS. This seems to mostly do the right thing. Unfortunately, the preview image is often quite different from Adobe's default rendering of the raw file (sometimes the preview is fine, but the default rendering is a stop too dark). I've seen this, to a much lesser extent, with D70 raw files, but it's quite annoying with the D200. I can only hope this is better if you use CS2 with the newer Adobe Camera Raw.

- An "uncompressed" NEF file is 15-16MB, allowing you to fit 60 pictures on a 1GB card. If you turn on "compression", the files are half that size. Annoyingly, the remaining-shots counter still says "60" instead of "120" (in exactly the same way as the original D70 with 1.x firmware). I've shot both ways, but not scientifically enough to be able to say, with any certainty, whether there's much downside to using "compressed" raw files. It's worth noting that DNG files are 2/3 the size of the original NEF files, while theoretically containing the same exact information. Proprietary raw files are stupid.

- The D200's autofocus and metering seem to be a real improvement over the D70. Autofocus is quite fast and accurate, both with screw and internal-motor lenses. The metering is conservative, just like the D70. The auto white balance is no significant improvement over the D70. You still have to tweak it afterward if you're a perfectionist. I shot a bunch of outdoor people pictures with the built-in flash for fill, and the exposure was dead on perfect. Very impressive.

- You have to crank up the sharpness. No big deal. Yeah, there's high ISO noise. Minor deal. What takes getting used to is shooting at ISO100 when you're used to ISO200. It's a big difference. And all that extra resolution? Not really a big deal either. I've made 12x18 inch prints from my D70 and they look fantastic. I'd much rather have 6 megapixels that went happily to ISO6400 than 12 megapixels that barely get to ISO800.

- Did I mention that the commander mode is a big improvement over the D70? I love hand-holding my flash and letting the camera remote control it. On the D200, you now have the option of having the final exposure include both the internal and external flash, and you can dial in separate exposure compensation on each. Very slick, plus all of those settings get saved in the custom memory settings, so you can flip quickly between different tweaked settings.

- Tweaked setings... there are tons of things to tweak on this camera. I read the manual carefully, and I think I still don't understand half of it. Sure, it says that you can remap this or that, but it doesn't say why you might prefer one setting over another. If I were going to buy one of these for real, I'd buy Thom Hogan's ebook, even though I never felt like I needed it for the D70.

Conclusions?

I'm keeping my D70 until some time next year, when I upgrade my whole pipeline. This is largely waiting on Photoshop CS3 (and/or Adobe Lightroom), plus upgrades to my computer (to process the larger files, faster) and to my memory cards (if you want to shoot raw, uncompressed, you really want a 4GB card). I'd also just assume wait to see what Nikon cooks up as the replacement of the D50/D70/D70s cameras. Maybe they'll make my dream camera with the better high ISO performance.

(And, yes, I know that the Canon 5D is the current king of high ISO. My friend who loaned me the D200 also has a 5D. We're planning out a series of comparison tests. If you've got ideas of something you'd like to see tested, head-to-head, post it here.)