This is an excellent resource. I started using Darren's Versatile NPCs when he posted the first set on Reddit and ever since, almost half the humanoid NPCs my players fight are taken directly from this excellent set. The Monster Manual and Volo's Guide are a great starting point, but I was constantly tinkering with stats to keep from one-shotting my characters with a powerful mage or overwhelming the map with a million guards. His characters fill the CR void with solid, memorable stat blocks that I can use again and again in any setting. At this point, I can't imagine running Tier 2 games without this PDF.
[5 of 5 Stars!]