Have tried it a little bit and come up with this ...
+ Easy to use as it is logically made.
+ Ability to speed sync.
+ Can be remotely operated with the built-in flash with TTL
(Run the D90. And when you're indoors or similar, worse outdoors).
+ Many useful accessories included, 2 Color, Diffusion Dome, foot.
The negative (however baubles!)
- State between offremote is a bit tricky and may require two hands.
- The button for the battery cover is a bit tricky until you learn ;)