Honestly, most all web servers have the issue of crappy documentation mated to pointlessly convoluted and complex configuration. It's an ongoing problem that's likely never to be addressed because the people who make these systems seem to think it needs to be that way.
But IIS is in it's own little world of derp with its blatant lack of efficiency, security, etc, etc. That it is tied to windows for use is a perfect example of why it should NOT be used in the first place, given that using Windows for servers is like using Linux for a desktop OS. It can be done, but prepare for a degraded and crippled experience.
Just as I find Linux to be crippled as a desktop OS, with piss-poor font rendering -- parti cula rly kern ing of t ext -- neutered video card capabilities, degraded audio, painfully bad audio latency rendering it useless for realtime production use, half the hardware I want to use not even being supported, etc, etc, etc, I find Windows equally hobbled as a server OS.
I do not understand why anyone would choose Windows as a server OS or Microsoft technologies for web development. They do not have a track record that inspires confidence, and if you know the first blasted thing about the topic HOW they go about doing things is the antithesis of good practices.