Good luck getting a real opinion on Nightreign on the mainstream internet, Souls fanbases are rabid and will purge opposing opinions.
Which they don't need to do much since most souls fans are niggercattle.
as the worlds most devoted FROM Software acolyte.. Nightreign is fun, but flawed.
its fun to have bite size power scaling Souls adventures, it however, is flawed in that the map is small, doesn't have enough variance (there isn't randomization but just handful of seeds) and some potential encounters/camps are leagues harder than others for the same reward.
the various characters are fun an different, but there is a notable stinker, the BIRD MAN, who while "fun" is 2 power scaling tiers below literally everyone else.
the addition of Deep Dives or w/e the hardmode is added a ton of variance to the game which it needed, and a ton more customization, and the new little expac added a ton more.
some of the bosses are some of the best boss spectacles I've ever seen, visually, musically and all that, including the Final Boss who has one of the best tracks in the series.
https://www.youtube.com/watch?v=RIyqbsKxRsE
the game feels more like a love letter to the entire "souls" franchise, while also an asset mash, however they aren't that cheap.. Artorias got a whole new remade fight with a second phase for instance, however fights like the Nameless king show their age.. what was once a pretty hard super boss, is now a joke, because he didn't get changed at all.
is it worth the price? eh for me it is because I'm FROM's greatest soldier, but buy it on a small sale, you'll absolutely get a hundred hours out of it.