Nice work! I like the weathering. I've built one sub myself - was the Gato in 1/144, but I think yours looks more detailed than mine, even in the smaller scale. Those rust stains are subtle but real looking. I've got the 1/72 Type VII in the stash - this may be the year to break it out.
By the way, don't put your submarine on a shelf immediately below the space on the wall where your vintage M1 Garand is displayed. Plastic, paint and glue are no match for gravity, solid walnut, and steel. Ask me how I know. 