I can't compare to other sub games, but I do appreciate complete immersion, and SH3 + GWX3 most certainly delivers in that regard. I strongly recommend giving it a go, and then post back here when your first depth charge attack shatters all cookies cutlery!
As for learning it : I did without even referring to the manual, admitedly not playing at 100% realism, but none-the-less a very easy game to learn.
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