I ordered a Xiaomi Mi6, and received it yesterday. My experience with Gearbest was good, but the DHL clearance department was a pain to work with.
The phone was USD 419.29 (didn't have the discount code at the time), plus USD 16.51 for shipping + insurance. Shipping was via DHL.
For some reason my postal code was deemed a "remote area" by DHL, which would've incurred a USD 35 surcharge. Gearbest let me know shortly after placing the order, gave me the option of changing the address or shipping method. Not sure if it was a mistake or not, but I just changed the postal code to a neighbouring one (same town).
So Gearbest marked the item as USD 100 on the Commercial Invoice packaged with the item, instead of the actual value of USD 419. I got the correct CI from Gearbest soon after placing the order, but getting DHL to update the details was a pain. After they sent me the first customs invoice with the wrong amount, it took about 5 phone calls and a couple of emails over 3 days to get them to correct it. While their standard support line is quick on the phone, their clearance (customs) department have a waiting time of 6-10 minutes for every call, and they don't respond to any emails.
Once they corrected the customs details, I had to pay R 1520 for customs. This is R 921 in VAT, R 449 for code "12B", and R 150 for DHL "Disbursement Fee". I have no idea what the code 12B is, but at this point I couldn't handling dealing with DHL anymore, and just paid the full amount.
Next time I'm just going to assume that the CI supplied with the package is correct, and not try to update it - way too much hassle.
Overall it took 2 weeks (14 days) from placing the order to receiving it. This includes a 1 day delay for changing the address, and 3 days for the clearance issues, so overall it's pretty quick for something coming from China.
Although I haven't had the time to test it properly yet, the Mi6 itself looks great so far. The only issue so far is that the US -> EU adapter for the charger that Gearbest included doesn't really fit into most sockets, so I'll probably have to get a different one.