I been playing Wals as my main basses since 1991. I have two Mark IIs 5s (fretless and fretted) which are on the heavy side and have just a little neck dive...but not overly so or uncomfortably so. Not any more than the Jazz basses I own. I also have two Mark III 5s and they balance perfectly and are lighter...the most comfortable basses I've played other than a custom 4 I had made that was actually carved to fit my body.
Sound-wise they have never gotten anything but great praise....live or in the studio. The B-strings are wonderful. Overall their sounds are fantastic. They cut through the band, they have wide and great bottom, full through-out the ranges and I haven't found another bass yet that I can get as much sound from without any equing. I use them in many styles of music from jazz to ethereal, to progressive-rock to singer/songwriter, etc.
The construction-values on my 4 are all great. Just really solid instruments. I have heard some complain, but this mostly was from the era when Pete was having health problems and production was backing-up. Pricing for my Wals ran as low as $2500 to a high of about $4200. The one I ordered new right from Pete was in 1992 and cost $3400. The most expensive ones are the used Mark IIIs I have and purchased in the last few years from a couple of fine gentlemen in the UK. Taxes/duties and shipping add quite a bit!
As far as the neck shape, I like it so much that when Joe Zon made me a bass, I had him make the neck to be very close to the size and shape of my Wals!
Of course, somewhat, this is beauty in the eye of the owner, but there are enough performances and recordings out there to substantiate Wal Basses' true value as great instruments.