Excellent
The constant sales, the wide variety of games, the accessibility, the ui and the customisation are all reasons to like Steam. I also never had any issues with the Steam support. On top of that, the fact Valve is still a private company and therefore not dependent on the highly questionable demands of shareholders, is a big plus. The only negative to me, is the Steam community, because parts of it are extremely toxic and especially the community moderators are comparable to your stereotypical reddit mod, but that's not Valves fault.