I was tasked to integrate Fastly into our infrastructure having not done any configuration with Varnish (VCL) before. ~10k req/s

VCL can be challenging for complex flow control (IMO), but it is made easier with Fastly enhanced/custom VCL modules.

Their documentation was good, and the Fastly support team was excellent. Their sales engineers gave us a baseline configuration that suited our needs and were quick to answer any followup questions.

Haven't noticed any downtime or response delays to date.