Not very. I have a section on this in my book Rollback. Here are a few links as well:
http://tomwoods.com/blog/the-glass-steagall-myth-revisited/ http://tomwoods.com/blog/repeal-of-glass-steagall-had-nothing-to-do-with-the-crisis/ http://tomwoods.com/blog/deregulation-caused-the-financial-crisis/