If you are not using it get rid of it.  Buy a mint 645NII on ebay and if you
don't like it (doubtful) sell it.  THe zoom lenses go cheap there too.
Watch auctions there for several weeks if you haven't bought camera
equipment there before bidding for real.

I used to own one before selling it for digital gear, but it's a very nice
camera. I liked the controls, which were designed (IMO) by photographers and
not gadet freaks. It's very simple: put both the aperture ring and shutter
on auto and you've got programmed auto. Slide the aperture ring to an
f-stop, and you've got aperture-preffered auto. Move the shutter ring to a
speed (with the aperture ring on "green") and you've got shutter-preffered
auto. Other functions are handled by simple slide switches and levers.

Lenses were a mixed bag for me. The zooms cover nice ranges, but aren't
sharp across the board, and pale when compared to Pentax's primes. They're
not bad, but the primes are much, much better.

AF is very good, and snaps into focus quickly and accurately. Film loading
is easy, as well, but there are no interchangeable backs, just film inserts
that can be pre-loaded.

Handling is first rate for a MF camera. The grip is good, balance is nice,
and the viewfinder is big and bright. Noise is OK, not too loud but quieter
than the 67II, for sure. One thing that prevented me from getting a 67II was
that damned mirror slap. Couldn't live with it.

Anyway, if you're staying with film, it's a nice choice. I sold mine when I
starting producing nicer images with my digital stuff (a Canon 5D). Based on
the time I spend with my 645NII, I don't think you'll miss the 67II at all.