I've built the Tamiya kit, and it is a great build. The level of detail is good, but to get the most out of the kit you really need to add a Gold Medal Models photo-etch set. The fine rails and other details can't be molded in plastic so they look better with PE. I haven't seen the Academy kit, but there's no reason why it couldn't be as good as the Tamiya kit.
The Tamiya kit is not too hard to build. It goes together in a series of sub-assemblies. The only fit problems are with the deck pieces, they leave a gap at the joins. Apart from that I had no problems during assembly. It was my first ship model too, and I got it together, so it shouldn't be too hard a build. Her's an online build of it:
http://www.rollmodels.net/nworkbench/onlinebuild/Bismarck/part01.htm
hope this helps.