I like the U-Boat. I really miss OLC GUI. And I'm much more of an expert in the fleet boat than the U-Boat. It is too easy to sink obscene amounts of tonnage, but obscene tonnage is always a lot of fun for awhile. The mods will come to knock that down to size.
There aren't enough escorts. I only ran into five with two BBs and a battlecruiser. They were too easy after my GWX and TM experience. I didn't like that so much. But I had more fun than I should be allowed to have with the add-on. I recommend it without reservation.
Learn the Fast-90 technique in the U-Boat and you don't have to worry about range or stale data ruining your shot. Check out this
provisional link and I'm fishing for suggestions to improve the instructions. Illustrations will be inserted before it finds a permanent home. I had trouble understanding Wazoo's instructions, so I decided to take on repopularizing his great technique. It was the basis for the Dick O'Kane fleet boat method, so I'm returning a favor there.