Yes buggy it is, but with a few strong coffees you can overcome the issues and still have a good patrol
My first 3 or 4 patrols were confusing as hell, Now i love this game, your eventually overcome the bugs and find a new way to play it.
I had the "sub sinks on dive" problem whenever i get a mission near Sea of Japan cause they consists of heading in there right in the
DRAGONS DEN
and deploying troops or photo recon & getting attacked by Aircraft all the way out, no mercy for a green captain and crew, so naturally there are times your have to crash dive only to sink to the bottom. In one career i couldn't get out of the area. Makes ya think tho, Man WW2 US submariners had some really dangerous/suicidal patrols that it amazes me everytime im leaving the sea of Japan, submerge and like a caged tiger feeling very threaten! And this is just a game. Imagine what it would of been like in real life.
Sry can't offer ya the real help, just dont give up on SHIV yet!
Check the mod section there are a few goodies out and coming out that will improve the gameplay till at least patch 1.2 is out.