If your first page takes longer than 15 seconds to load you're in trouble. Once loaded, pages that have poor design and faulty navigation turn people away, frustrated. Another faux pas is requiring them to download software or update their browsers. In reality, you are requiring them to spend the next 20 minutes to 3 hours downloading software to see your page, well, it's not going to happen. Navigation should be simple to use and easy to figure out.
Difficult navigation runs people out of lots of web sites.
The Internet, like most frontiers, is a place where the novice is at a disadvantage. The net is not rocket science but it is not easy either. To explain how the net is, here is an everyday example. Or buy an airline ticket and fly to London. You just want the right results, to do business in London.