Well I managed to get my hands on a D3x for a short while and yes it is amazing. The files from that camera blow everything else I have seen away, compared with other DSLRs anyway. Actually the files are comparable with medium format digital backs and surpass both 35mm and 120 film that's for sure. Now I am not going to run an in depth review here. There are plenty of great detailed reviews around, what I am going to tell you is my opinion of the camera as a working photographer specialising in wildlife, nature and adventure sports photography in as few words as possible to help you decide what is best for your photography.
Firstly the D3x is based on the D3 body so its controls are the same, great from a workflow point of view. You can just get on with shooting as you have with the D3, that is if you didn't have to wait for the camera to crunch these huge files! After shooting with the awesomely fast D3 the D3x feels like it runs at glacial speed. A whopping 1.2 frames per second is slow even for my landscape work. I will write that out again so you know it isn't a typo, one point two frames per second! I have the buffer upgrade on both my D3s so it feels like I can shoot at 8 fps for ever but the D3x on the other hand, well you have to wait. This goes for downloading and processing the files too. My desktop machine can handle the files, (a quad core 3GHz machine running 8Gig of RAM) but my notebook (a 2 year old dual processor 2GHz Dell with 4Gig of RAM) well it dies. Lightroom, Photoshop and Capture all struggle keeping up and as I do a lot of processing while out on the road I would have to factor a new laptop into the purchase as well. Speaking of dollars how well does an RRP of $12,000 fit in? Well it is a lot of cash but not too much for such a camera that can holds its own against >$20,000 medium format backs. All the complaints about the D3x costing too much is just crazy. It is worth what people will pay for it and that is what Nikon are asking. I think Jaguars are expensive but I am not complaining I just won't rush out and buy an XJ8...
So Will I grab one? No. Not just yet. As a day to day camera I prefer the speed of the D3 over the file size of the x. The combination of the extra expense and the slower camera does not add up for me and my business. I do have a couple of projects coming up where the extra file size will be awesome but that is in the future and things and opinions do change.
And here is an example of the fantastic files this thing produces. Not my normal thing but check out the single hair in the left of the frame. Thjis is a 100% crop taken from the image below. And Little Miss Stubborn there has very fine hair! Awesome stuff. This is where I think this camera will excel, portraits and studio work where speed (fps) isn't critical.
And where to from here? How about and D700x? that sensor in a slightly smaller package would be awesome and I would drop 10 grand on that in an instant.