I am the author of jeviz.com. Currently it is only for US locale. Immediate benefits are you have more options for search sorts. For example most choose a department and select "Most review" sort option to sort by number of reviews which is not visible in Amazon.com site. When you login you can save your search parameters and synch your mobile, desktop search parameters. There are about 50,000 categories in Amazon you can do full text search for categories. There is advanced book search more accessible than Amazon advanced book search. Please tell me what are the features you want more.