Here’s the summary of article from Thom Hogan: “The D40x retains all the things that are likeable about the D40 and gives you a 10mp sensor that produces images that are arguably slightly better than the D80 can produce (at least for JPEG files).”

Drawbacks

• Kit lens blues. The 18-55mm is a more than decent lens, but I’d like to have the option to buy a body only (you do with the D40x). The D40 would have been killer with an 18-70 VR or 18-135mm VR, by the way. The current purchasing option is a bit limiting.
• Nother new battery. Did we really need another new battery just because the camera is a smaller size?
• Not for the late-to-the-party film converts. If you’ve got mostly AI, AI-S, and older AF lenses and are just now getting round to going digital, the D40 (or D40x) isn’t the camera you want, as you’ll be resorting to manual focus.

Positives

• Small and beautiful. Makes you wonder why Four Thirds designs (e.g. Olympus) were necessary. And for a consumer camera, the frame rate, mirror return, shutter lag, and autofocus are fast enough to feel snappy.
• Most of what you need. While it would have been nice to have a DOF Preview button, everything else you’re likely to want is there, including spot metering.
• Excellent Image Quality. State of the 6mp art. State of the 10mp art. Enough said.

Website : Nikon D40 and D40x Review by Thom Hogan