The deal of the century right now (end of 2011), as with very little money you can get a superlative camera. I suspect this will continue to be a great opportunity for some time to come
+ superb customization and options/features
+ forget the "semi" prefix. This is a true pro camera, in its build quality, set of features, and complexity
+ stratospheric value, it's incredible how "much" camera you get for your money
- a very complex camera, clearly not for people who don't want to spend time on learning it
- no video (if you're one of those modernists who care about fluff like this)
- some people will find 3200 & 6400 ISO noisy (they can go pixel-peep elsewhere while true photographers take photos with the D300)
- advanced users who need a photographer's camera with a lot of customization
- people who have grown out of their smaller cameras AND are patient and willing to learn
- pros who need a true pro DX body for tele work.
- people who want to use cameras in auto mode - there is no auto mode(s) in this camera
- people not willing to spend time and effort to learn their camera
- people who want/need small/light cameras
Fantastic value. Impossible to beat. Ever since the D7000 came out, the D300 cameras are being dumped en masse. As a result, their price right now is so, so much lower than what you'd expect for a camera so rich in features. The 51-point 3D tracking autofocus, the 12MP sensor, and the simply matchless set of customization, is definitely, definitely worth the money.
Of course, this is a camera that is not simple to use if you're a novice. For people who know that they want it, this is simply superb. For those who hesitate, you could consider it but ONLY if you're willing to spend time with it and learn its secrets.