It’s quite alright, but the platform hasn’t really grown in a while outside of its available catalogue. Gog galaxy is still in beta I think and it also still has no Linux launcher yet. Still good for the no DRM part tho

It’s pretty good they do a good job of keeping old games available in a decent state

You can download offline installers that don’t require an internet or licence key to install, so if you back them up I’d say you own them to the same degree you’d own a game on optical media