If you are talking about Vladimer's Akula II hull kit, no finer hull exists for this boat. Detail and workmanship is top shelf. Worth the money. And if you have any problems, Vladimer is always helpful.
As far as how difficult a build, it is just a fiberglass hull with details, a prop, photoetch, and decals. The usual things go to putting it together.
Many here, including me, will be glad to answer questions and guide you through.
I do have one I am putting together now.
SubCommittee Vice President 2006-2008
Author-Russian Submarines, Guardians of the Motherland
Member-Saint Petersburg Russia Submarine Club