I use it, and have used its predecessors since transitioning from film to digital in 2006. For a long time, Nikon's software was arguably the best tool for squeezing optimal quality out of a Nikon-generated raw file. This is probably because Nikon has never fully disclosed information about its raw files, so other software developers have had to reverse engineer some elements. Over time, however, other software has narrowed or perhaps closed this quality gap. As I'm used to using Nikon software for this purpose, I haven't switched.
I've never loved the interface, features, or performance of this Nikon software, but got used to it for converting raw to tiff and a few other tasks. I then use Photoshop for all additional photo editing.
While this workflow fits me and my particular history, I'm not sure it's a good fit for someone else. Nikon makes wonderful cameras and lenses, but software has never been its strong suit.
A nice thing that has been consistently true in all versions of Nikon's raw conversion software is that the defaults render very closely to the look of Nikon jpeg files. If one likes the look of Nikon jpegs (I do), it's helpful to have that look as the starting point when converting raw files. This way, any deviations from that look are by choice.
It may bear mentioning that if one doesn't alter anything from the default settings, there is little or no good in shooting raw instead of tiff or jpeg. Where raw really shines is in capturing more dynamic range than tiff or jpeg, then permitting human judgment to be applied when compressing this information into another format during conversion.
--Jub