First good surprise: I did not feel at all confused by the controls, the grip and viewfinder information that remind me of my F601 (silver). In addition, the D3100 is simple to use, but can easily be "disengaged" to control the settings, and make photos "old". The picture quality is worthy of the reputation of Nikon, especially regarding exposure (Nikon is the inventor of the measure "multi-zone").
The integrated flash is powerful enough to avoid buying a SB400 flash that does not bring in direct light thing (prefer if need Flash with a higher guide number 30 - I myself have opted for Sigma ). Furthermore, this little flash distributes light very well and is not red eyes.
In short, for the price (500 euros month in kit), it has a datasheet well above last SLR range of environments from the end of the silver age. Moreover, the pleasure of presenting his eye in a viewfinder should give taste to all lovers who do not find their account with the current compact. A device altogether pleasant enough to get back to the "real" picture.