If you pick the right hardware and distro, there’s not too much trouble in my experience. I’m using Pop!_OS 18.04 on a Dell XPS 15 and on integrated graphics I can easily get 6–7 hours of battery life. And that’s not with a completely dimmed display and only using email. That’s doing some 3D work in Blender, CAD drawing in DraftSight, development work, photo editing with Gimp and Polarr…

So far I haven’t had any issues with WiFi, only one issue with a very specific Ricoh printer at a client’s office (which also doesn’t work on macOS by default).

On discrete graphics, I agree, battery life is horrible. 3 to 4 hours max. But when I need discrete graphics, I also need an external display, keyboard and mouse and power is never far away in that case.