I had hoped that there would be a resolution where JLC stood behind their production and quality but at the end of the day, I was offered $100 dollars, less than 5% of what I lost in bad product they shipped to me. I asked if they could just replace or refund and have been forced into seeking paypal disputes and credit card charge backs for "library" parts used.
I would say, if you you doing a small run prototype they might be quick, easy and cheap. If you are spending more than a few hundred dollars you are willing to burn, then I would think twice.
PCBBuy.com
AllPCB.com
PCBWay.com
Are all great alternatives with MUCH better service. We had damaged pcbs from PCBway in the past and they immediately replaced all the damaged goods.

In addition to just quality, the over all attitude and customer service of JLCPCB is completely lacking. I received multiple different stories about why my items were delayed (every order I placed shipped late) and what was going on. Even now, they are doing very backhanded conniving things like telling me, My boss can't approve a settlement unless you cancel the paypal dispute. When I say, ok, well how much will they approve if I cancel the dispute (which can not be reopened) they say nothing. It's a sham trying to get me to remove my only recourse.

This is my experience. I know other people have had better ones, but I think people need to be aware of this. If you have questions or comments, l please feel free to ask below.