On a small display that I usually want to watch digital movies on, it's fine. 720p is the minimum for anything I actually want to watch/enjoy watching. Like I said, a lot of stuff I have on DVD is stuff that is good to have that I'll probably never watch regularly

I like 4K UHD HDR Blu Rays very much and have a big TV to take advantage of them but I agree with gp that 480p is good enough in the sense that a good movie will still be enjoyable in 480p. And if you are engrossed in what you are watching you won't even notice the reduced detail. There are some DVDs with atrocious encode quality with a much lower effective resolution due to low bitrate (i.e. multiple full length flicks squeezed onto one DVD) or unfortunate processing (NTSC master -> PAL DVD release or the inverse is to be avoided) but that's thankfully rare.

Now, 480i is something I'd rather leave behind but even that is a lesser concern than the content of the film.

Depends on screen size and viewing distance.