I don't have a lot of references that are not in Russian, unfortunately, BUT...
Here is an old thread from my visit to the D-2 submarine in Russia, an awesome exhibit and arguably the oldest preserved war veteran sub (i.e. the oldest-built sub that went out, sank ships, returned from patrol, and became a museum at the end of its service).
http://www.subsim.com/radioroom/showthread.php?t=124914
Give it a look
and you can always start looking here:
http://en.wikipedia.org/wiki/List_of...rld_War_II_Era
The Soviets didn't invent everything themselves of course, but they generally kept up. If you look at the subs, you'll notice that in a lot of ways they combine features from other nations' subs. Their main classes, in a lot of ways, look like a hybrid between hulls that look a lot like German U-boats, and tower structures that look like early-war American fleet boats. Some of the equipment was essentially copies - for example the S class (
http://en.wikipedia.org/wiki/Soviet_S_class_submarine ) was built on early plans for the German Type IX that the Soviets bought. The Soviets generally benefitted a lot from the research that the Germans did abroad between the wars, when they were still respecting the Versailles treaty and thus not building any subs of their own.
One big difference is that the Soviets essentially stopped sub development and construction when WWII started. All of their efforts were directed at the ground war (for good reasons), so the improvements throughout the war were minimal and the crews mostly had to make do with what they had - while the Germans and the Americans made big technological leaps and accelerated their production. So by 1945 the Soviet equipment was as obsolete as the early-war Type VIIs and Type IXs. Needless to say, they raced to grab what they could from German technology when the war ended, including the XXIs and XXIIIs.
They still did a pretty good job in the war, all things considered. All their subs were built and equipped at home, and were able to stay operational even in extremely bad conditions. They weren't better than German or American boats to start out with, but they weren't worse either. I'd say they were about on par, and certainly the M and Sch classes worked well in the tasks they were designed for (patrol in restricted coastal waters).