I think they had their hits and misses. This is a beautiful bird, so is the Sukhoi of the same generation. It's quite a bit different than the MiG-25's concept of "Let's slap a cockpit and wings onto a couple really big engines." But even that is more elegant than the butt-ugly MiG-23.
Maybe they just had some different designers in the Vietnam era, because I've seen a MiG-15 up close, and it looks very nice.