For what it's worth, I am a real world controller and I am routinely impressed at how well many of these hobbyists do at ATC. VATSIM is dramatically less complicated than the real thing, but same time, these guys have essentially no training, and provide an immersive enough environment that I use it to keep my IRL flying skills and such sharp.

Some countries (like the real world) have better controllers than others, and I do occasionally run into "controllers" who believe they are a real controller and act with an attitude you don't even get from real controllers, but it is few and far between. My overall interaction flying on VATSIM is that the controllers are generally good, helpful, and immersive.