I bought a new Camera last week - due to arrive today .. shortly I hope :o) I'm very satisfied with my old (9 months) D40, but it has some short-comings that have been eating at me for a while now, so naturally I needed to upgrade :o) - and here's my justifying it to myself :o)

Lens compatibility
The D40 is limited in the sense, that it's the first Nikon camera to ship without Auto Focus (AF) built into the camera house. It relies on lenses built after 2006 with AFS (basically AF motor built into the lens) - which means that any older lenses won't auto focus on the D40. New AFS-lenses cost upwards of $800! Older non-AFS-lenses come used at maybe $50 or $100. Another issue is the lack of "metering" (roughly: "measuring of light") using older lenses, but that's minor compared to the AF.

Adjustment is a bit coarse
Well.. it's a "cheap" camera, so naturally they cut some corners. ISO range is a bit narrower than the other models, white-balance tuning is done i Photoshop - not on the camera, bracketing is a manual operation, no aperture wheel, I could propably go on.

So I went and bought the new D300. It's a magnificent camera (or so everybody says), built in magnesium and with full weather-seal (no dust or moist getting into the camera), compatible with every Nikon lens built since 1979, all the bells and whistles and much improved performance at high ISO (better at taking good pictures at low light), customizable in a ton of ways and basically God's gift to any amateur photographer. Can't wait to get my hands on it.