It's fine? Might be worse than Windows, but unless you spend long times away from a charger, it doesn't really matter, does it?

To answer your question, I might probably get around 5-6 hours of video playback (local files, not streamed) on my generic cheap x86 machine from 3 years ago from full to empty, but I don't have the windows equivalent numbers, and I limit charging at 80% and charge at 40% anyway so I don't actually go through a full charge cycle.