I use this to increase the resolution of my 1080p external monitor (zooms it out and makes everything look crisper). Also fixes my 4k external monitors that Apple makes look blurry. A must have for me.
I had to use virtual screens (which their wiki notes as having drawbacks) since the other option wasn't working for me. The only downside I've found so far when using virtual screens is that sometimes when an external monitor with a virtual screen has nothing moving on it, it starts displaying a frame that used to be on that screen like 5 seconds ago. When i move my mouse to that monitor and wiggle it, it updates back to the current display. Mildly annoying, but it could be an OS limitation so I'm ok with it.
