Edward, Do take note of where and from whom you are buying this camera. NDs were part a large robbery from a Contax USA warehouse recently.
I also cannot sit idly by without providing a few experiences of my own. I have a ND and all the lenses except the 400/4 and macro (which I don't need due to using the C645, 350/4 and 120/4 macro on the ND with an adapter). I also have had extensive experience with a Nikon 1Dx, Canon's D30, 10D, and now a 1Ds.
Using the ND is labor of love. Like many Contax AF cameras, it is power hungry compared to other DSLRs. IMO, the chief issue is the use of AA sized NMH batteries.
While the batteries have become readily available in strengths of 2200 mAh, they do NOT hold their charge while not in use. If the camera sits for awhile it will be dead, or close to it when you go to use it. When I use mine, it has to be a pre-planned event so I can recharge the batteries overnight for use the next day. It does not have anywhere near the efficiency of a Canon D10 with its batteries that DO hold their charge for months and months, and last, and last, and last when shooting (even when using all the functions including AF and constant LCD review).
So if you are a more casual shooter, the battery issue WILL be an irritation, mark my words.
Next is the RAW function. You cannot review RAW files on the LCD as you shoot. This is one of the major drawbacks of the camera. Plus, the RAW developer provided with the camera produces a moiré pattern visible in most ISOs above ISO 80. Some ND users like Irakly of this forum have devised a work around to minimize this issue, but it's a pain in the neck to do. 3rd party RAW developers like the amazing one included in PhotoShop CS (8), do not support the ND, but do support RAW development of all the NIkon and Canon models. So we are stuck with the one from Contax.
Lastly, the buffer storage for ND Tiffs and RAWs is the worst spec of all the DSLRs. You cannot shoot Tiffs or RAW in any continuously significant manner.
Now, all that said, The camera can been used in J-Peg-1 which CAN be reviewed on the LCD, and the buffer problem basically disappears. I find that even in J-Peg the tonal capture to be better than most other DSLRs, IF your exposure is accurate. You cannot underexpose with this camera very much compared to all the other DSLRs (probably related to the limited ISO issue). But when it's on, it produces superb images.
And it should be noted that I grudgingly love the camera enough to be looking for a second body to buy.