I have owned a Nikon Speedlight SB 600 flashgun for a few years and use it regularly. It never fails no matter what light condition it is. The i-TTL mode works perfectly with both my Nikon D70 and D700 and it can always get the right light and exposure.

The remote control and the little stand which comes with the flashgun is very useful for creative lighting and the automatic light/exposure control works equally well in the remote setup. The automatic setting works well in most situations while flash compensation can be easily set up by the camera or the flashgun buttons. Although the minimum distance in the specification is 0.6m I have no problem even with macro photography (about 20cm). There is a build in the wide flash adapter which could act as a diffuser. The head can rotate 270 degrees and tilt 90 degrees. i-TTL works well in any position with reflected or bounced lighting. Charging speed is really fast and it works well with D700 even in high speed continues shot mode. The auto focus and auto high speed sync work perfectly with my camera and lens

As it works well in most cases without needing to touch the menu system, you do find it is not that easy to work though the menus if you occasionally need to. There are a few occasions that I have to refer to the user manual to get it right.