I have been using AliExpress for quite some time now and never had any problem with any order unlike ebay which i have had plenty of problems with different items i have ordered.
on AliExpress as someone else stated the seller does not receive the money until you give feedback stating you have received the item and are happy with it also i have been told if a seller has more than a couple of problems then AliExpress closes their account and will not let them sell on it again until they have sorted out there problem with the buyer.

also under UK law you get a guarantee from your credit card as you are buying the items from the credit card company and not from the seller so that is another layer of protection for you.

regards Poppy Ann.