Been a customer for many many years now, and I think they deserve a 4 fully.
Items always arrive, and raraly late. If an item does not work, you can easily send it back (although, last time had to do it, you had to pay for return shipping, even if the item came broken).
However, the customer service is sometimes hard to reach. But, the worse thing is that you cannot always be sure of the authenticity of the items (especially electronics) from the many third party sellers. And some of the positive reviews on these items are clearly fake.