they are really clean, a very fundamental kinda tone (think a really good jazz bass with a cool 3 band eq), try and play a BBG or BBN from the mid to late 90's as they are all based off the same thing just the slight difference in the build and electrics, the BBNE2 is neck through and has jazz style pickups and a fully contoured body, where as the BBN and BBG are bolt ons with jazz (BBN) and jazz styled soapbars (BBG) with a 2 band EQ (im sure you could get some with a basic 3 band too, but not the nathan east sig one). you could also get them passive too.
i have 2 BBG5a's one is stock and one has a P5 and MM pickups in, both have a similar tone (due to construction) but with different tonal qualitys from the pickups. my stock BBG is my go to bass when i just want a solid tone. as for specs string spcing is smaller than fenders more like an EBMM, as for playability i have actually been documented to fall asleep playing and carry on till the end of the tune spot on, hows that for playability?? i have also fell asleep holding her from just sitting around the house playing till i fall asleep.
from my experience yamahas are nowhere near as shoulder crushing as fenders (my jag and P are way heavier than my BBG5a's) but they are most definatly solid, actually i prefer my yamahas for build quality, actually i just prefer my yamahas full stop. you may want to check out the yamaha club thread im sure one of us has one.
check youtube for some NE stuff, chances are you already know some of his stuff (he is claptons main bass guy, and a MAJOR sesion go to guy)
here is a typical example, he actually uses his bass to the full throughout this clip
http://youtube.com/watch?v=CJ0wupn_kRw