You can view your bookmarks in three different views. The main view is a small list with the websites favicon, giving you a good overview.
The second view is a big list, showing the thumbshot of the website. Sometimes it´ easier to find a website with this view. Please allow some time until your thumbshots are created.
The third view is the thumbshot view, displaying the thumbshots horizontally with less information, but showing more website thumbshots in less space.