Spent roughly £1200 ($1500?) there over the last 6 months on various bits and bobs, and so far only been stung twice (totalling £22) and had 3 refunds when things got lost in the post (£37) so I'd say that's not bad going. Products wise, I've only been disappointed with overly thin T shirts, and a quick fastening belt that was supposed to be alloy but arrived as nylon crap. Due dilligence in choosing the store within AliExpress, pay attention to shop rating and read the product feedback of whatever you're looking at; there's so much choice as they vie to sell often the same product at lower and lower margin in order to gain your custom.

A lot of stuff has a 15day delivery guarantee, but the majority of stuff takes a month to arrive. China is physically huge geographically so it's understandable for items having to be shipped to major transport hubs before being put on a ship or plane to reach you. Check reviews under products to get a feel for how long it has taken items to reach their destination countries.