Thank god for the imperial units fix. I also love the new dark UI at night, very useful. The crew talks a lot more now, like in SH3, such as when you are getting attacked, etc. The AA crew seems to respond better, and I haven't seen any planes crash on their own yet. I also haven't seen any massive FPS slowdown yet. Haven't put the deck gun through very much but it appears to be fixed.
The ghost crew still happens periodically. The A button causes a CTD now. (from what I hear) Also, I wish there was a % hull strength like in SH3, or is it now that if I fix all my bulkheads I'm back to 100%?
My air search radar still picks up boats, and reports planes as boats. Sonar still won't work on the surface, but I think that's a design decision, not a bug.
I have only played one, short patrol so far. I got sunk about 100nm west of Midway! It was all carrier based aircraft, coming from the north, and I was trying to find the carrier but alas, I lost the battle. (At least I hope it was a carrier, and not random planes spawning in the middle of the Pacific)