I guess most of the weapons that fought WWII in the first few years were pretty out dated - hell, never mind design, some WWII ships even fought in WWI, though I guess ships have a longer shelf life due to the time and cost of production

But yeah, the Type VII and IX are classic examples of a weapon being pushed way beyond its effective operational life, they were technically obsolete as early as 1941, they should have been replaced mid-war.
The main British sub classes S and T were quite badly technically flawed come to think about it.
-Oval shaped pressure hulls to accomadate 6 fore tubes (no where near as stong as a cylinder).
-Torpedos had no TDC or gyro and were gas powered only (at least the detinators were reliable though)
-Lack of external tube doors on the bow tubes created alot of drag.
-External Torpedo tubes mounted outside the pressure hull, were often prone to failiure and could not be reloaded at sea.
-They were Slow, even slower than their predecessors such as the P, O and R classes.
-They were ASDIC equipped, why? not suprisingly British submariners never used it!