I agree with most people posting here that Nash basses are not the prettiest instruments.
The sunburst I have is really yellow and might be one of the worst sunburst I have seen.
The magic of these basses is in the way they play, feel and sound. To me these are the most important factors. I like pretty basses too but playability and tone is what matters to me and Nash excels at that. I have the feeling the Lollar pickups they get must be to their specs because I have owned a set of regular Lollar purchased new directly from Lollar and they sounded nothing like what's on my Nash. Tone is driven by the whole instrument, naturally, but still they sound a lot better than the Lollar's I tested on my Fenders.
I certainly see that Nash basses are not for everybody but they feel and sound better than the Roadworn Fenders I have played. They sit somewhere between a new instrument and a vintage instrument. Compared with the $6,000 to $9,000 1962 to 1966 P basses I played they are very compelling.
I noted that some pros are keeping their vintage instruments at home and touring with Nash instruments. Glenn Hughes mentions in Bass Guitar Magazine (UK publication) of June 2014 that "Bill Nash creates basses that are astronomically brilliant" and that he tours with them.
I recommend reading the following article which I thought was quite interesting and gives an insight to these types of instruments:
http://www.premierguitar.com/articles/5_Pre_CBS_Inspired_Bass_Builders_You_Should_Meet
Again, what I look in an instrument is playability. More precisely, I want the bass to stay out of the way of my thinking. A great bass is a bass I don't have to think about when I play. If my hands are flowing, the music flows and magic happens. If I have to fight the instrument then I sound bad.
Nash lets me create the music, they kind of disappear when I play them and that's exactly what I love. For that I think they are a musician's instrument.