The nikon flash system is quite good IMO
I find it easy to use because it is TTL or manual
in TTL mode dial in FLASH EV compensation and results are great , hard to tell flash was used, also available when the flash is remote , it works in any mode PASM
it can be used in any shooting speed and it still works, although power gets limited
I usually expose for ambient light in manual mode, and fill in with flash in TTL mode
I can open a separate thread and provide examples , if that helps