I must start all this by saying that this is not a formal review of the camera, nor did I attempt to make any objective comparisons with existing cameras. I had the chance to try both the forthcoming Nikon DSLRs today, D3 and D300, and I thought people would like to read my subjective thoughts.
I do not intend to buy either of these cameras in the short term. For me the advantages that the D3 offers over the D2X I already own are mostly not relevant enough to my photography to justify a new body and housing (these issues have been discussed many times on Wetpixel, so I won't repeat them here). This could change if I get specific commissions or end up with a housing for a hypothetical D3x that also took the D3.
I would also add that I think that the D300 also out guns the D2X. It is a big step on from the D200. DPReview said that the D300 is as much as a step over the D200 as the D200 was over the D100. I am inclined to agree. Although the FX chip D3 is getting all the attention, it was the D300 that really exceeded my expectations.
Some opening remarks:
There is no doubt that the D3 is clearly a better all-rounder than the D2X. The high ISO is very impressive. The AF on both cameras is very nice. The D300 felt slights slower than the D3, although because of the smaller sensor had better AF frame coverage. I felt there was a small improvement over the D2X, but not massive. The LCD screens are massive. It was shocking seeing them next to my D2X. The viewfinder on the D3 was not as amazing as I was expecting, and I didn't like the exposure meter being on the right. The D300 viewfinder is much nice than the D200. The live-view is cool! AF performance under live view is about the same as a standard digital compact camera. This could be very handy underwater. For those who shoot a lot, you will notice the camera also has a more Canon-like exposure - less under exposure than a normal Nikon! I really liked both cameras.
I'll make separate posts below for each feature I have comments on.
Alex