Haven't held one - I'm in the process of putting my entire Nik V setup on eBay, and putting the cash towards a C-5050/PT-015 digital. I'm just not dedicated enough to UW photography yet to justify $4500 on just a camera and housing without any lenses or strobes etc. Spent a fortune on the Nikonos and I've used it maybe three times.
My Nik has been totally rebuilt - it had a seepage flood past an o-ring, and was just enough to fizzle the guts of it - so it's had totally new electronics installed, and the lens cleaned and rebuilt - basically a new camera in an old body. I'll be putting up a pair of freshly-serviced Ikelite 50 strobes, arms, brand new sync cord, tray, extension tubes, and some other leftovers at the same time.