The D300s remains a capable, even impressive camera. I mean, it's not like it got worse: The D300 retains the same sensor, excellent 51-point autofocus system, fantastic chassis build quality and ergonomics—just about the same everything—as the D300, and it still holds up 2 years later, mostly.
Low-light performance is solid, as you can see in the giant sample gallery here that walks through ISO ranges. We're talking fairly good-looking stuff up through ISO1600, though noise starts to creep in there, finally getting oogly around ISO3200. It's no 5D Mark II or D700, but it still stands up. Color saturation remains top-notch, and it seemed to handle white balance even a bit better than 5DMkII we shot alongside it at Giz Gallery last week. Bottom line, though, you're getting the same D300 performance. (Which means D300 reviews are still worth reading.)
• 720p video recording
• Extra SDHC slot
• More Active-D Lighting controls
• Tweaked button layout
What's majorly new in the D300s is video, and even it's not a whole lot different than what you saw with the D90, which also shot 720p video (and had a similar 12.3MP sensor). But, there's stereo input, and you can autofocus during recording—it's god-awful slow, so you're better off doing it your own damn self. Not to mention movies are capped at 5 measly minutes. And if you're still in live view, you can't actually watch the stuff you've just shot, since the playback button is how you adjust the display's brightness in live view mode.
The video quality itself is good, generally, but pushing past ISO1600, it starts getting a little dicey (Brian's shirt makes my eyes and ears hurt it's so noisy in this clip):
Beyond video, my favorite new addition to the D300s are the dual memory card slots, which were formerly a super pro feature. The extra slot holds an SDHC card, which you can use a number of different ways—continuing the storage over from the CF card, duping whatever goes to the CF card, or to save JPEGs from RAW+JPEG shooting. (Handy, since OS X and Aperture don't support D300s RAW files yet.)
And of course, one of the best things about Nikon cameras is that since the lens mount for their SLRs hasn't changed in about 50 years, you can use seriously vintage lenses (and save money), which is something we definitely took advantage of while shooting.
Here's the thing about the D300s: It's a great camera, no doubt. The problem is two-fold: At $1800, it costs the exact same as the D300 did when it was released two years ago, but beyond video, delivers no major advancements. There's no new pixel-squeezing camera tech here. The other part is that the very shortly forthcoming 7D from Canon is their first direct competitor to Nikon's D_00 semi-pro cameras, and it may make the value proposition look even less fantastic with what appears to be the most advanced video features of any DSLR yet. As it stands, the D300s is a tough purchase call (you can pick up a D300 for $150 less if you don't need video), and certainly not a necessary upgrade. But we hope to head-to-head the 7D and D300s very soon to figure out the best camera you can buy for about $1800.
If only Nikon had just given us the D400 like we'd wanted.
Dual memory card slots are a huge win
Good low-light performance, awesome color saturation
Two-year-old sensor costs this year's money
DSLR video still has a long way to go