Hi Marion. There are probably a few reasons you don't see many comments on the D3X.
Because of it's price there are far fewer owners of this camera.
It was Nikon's showcase model when it was introduced. My guess is that manufacturing and quality control were at a very high level.
The photographers that bought this model were most likely coming from other pro models that handled the same way as the D3X. So no learning curve. The current high performance, much lower cost cameras are being purchased by a much wider range of experienced users. The least experienced are making mistakes which show up in their photos and they're commenting or complaining about it.
There didn't seem to be a fault with this model that would draw attention to it. No focus issues. No metering issues. Nothing to comment on.
For me I'll have the D3X for a long time. I find it's perfect for what I use it for. The photos are fantastic regardless of what lens I have. I don't have any issues at all. It's like the D700. You can't take a bad photo. It's that easy to use. And I suspect you can say the same thing for the D3 and D3s.