I quite like The Rings of Power, but it does seem that it gets a lot of bombing for some reason, indeed. Critics are very divided so I'd recommend to keep an open mind.
Some find that it's slow to start, and it's not false. I remember similar reproaches about The Lord of the Rings was released, or even about to the book, criticizing how slow the plot was. It's a matter of taste. If you're expecting a series packed with action, maybe that's not for you.
As for discrepancies, it's the usual. It's been a while since I read the Silmarillion and other stories of Tolkien mythology, and even then I only read bits of it, so perhaps I don't mind so much because I'm not a purist. The original stories were very fragmented, so I don't think that it would be possible to make a series out of that without being creative anyway; Jackson did the same with The Hobbit. And while I agree it's not the same quality as Jackson's movies, it probably doesn't have the same budget either.
I've also seen critics about races being badly represented, except the dwarves. It seems to me that the harfoots are even better, that the humans are as expected, so are the elves, so I don't see where it's coming from. Galadriel is a bit cold for sure, which is normal, and she displays the same ease in combat as we saw for ex. with Legolas.
Something I don't like too much is how often they jump between threads, though I've seen worse. It seems to be the new fashion in series now, or perhaps it didn't bother me as much before.
they really shit the bed by introducing some stupid explanation as to the origin of mithril, and then tying the Elves's lifeforce to mithril? It sounded so stupid, and exactly the kind of stuff you'd expect from people not doing their research.
Is there any other "official" explanation about the origin of mithril? I haven't found any, and the legend / song told in the last episode didn't shock me. Songs and legends are often an embellishment of history so it actually fits pretty well.