I order from there quite a lot. I’m not really a fan of buying Chinese stuff but all the electronics are made there whatever you do and this way I’m cutting out the man-in-the-middle dickhead types who closed all the local factories and moved production to China just to push up the share prices.
I’ve always found it to be pretty good, remember that you don’t really deal with Ali that much, rather individual shops selling their stuff on there. I’ve had problems with stuff arriving broken before but I’ve usually found their customer service to be pretty amazing, they’ll often replace stuff without much fuss. I once ordered a Bitcoin miner before realising later that it was a scam, and Ali refunded me all the money.
The two main problems are that nothing on there is good quality, it’s all just cheap Chinese stuff. The second problem is that it takes ages for everything to arrive.