The worst place on the Internet for buyers! There are many scammers there. The common problems are:
1. Product not as described: No some functions, other color, materials, etc.
2. Product doesn't work properly, damaged, broken.
3. A seller may cancel a paid invoice and increase a price of a product.
4. A communication with the administration of Aliexpress is very difficult: no contact form, no email to send a message to the administration. Virtual Agent Eva (why not Adam?) is an interactive FAQ. FAQ is not good.
5. An escalation procedure of a dispute isn't suitable for buyers. You may add evidences, comments, messages when it's allowed by administration ("Awaiting my response" status) but the administration may allow or disallow such a possibility.
Enough?
Get rid of Aliexpress!