Great work!
I'm building this kit myself at the minute (just needs decals adding
then it'll be finished). I built it "out of the box" other than
replacing the aerials with metal wire and adding a couple of crew
figures (modified N-gauge model railway figures). I ought to have
replaced the ladder rungs on the conning tower with metal wire, as you
have done, but just didn't think of doing this.
It's a surprisingly small + simple kit, but builds into a nice-looking
model. It certainly makes an interesting contrast when displayed with
the Type VII and XXI U-boats in the same scale!
I wonder if ICM are planning any other sub kits in this scale. It'd
certainly be interesting to see some WW2 Soviet subs (such as the
M-class or "Malyutka", which wasn't much bigger than the Type XXIII)