Long-time Tolkien fan here. I have read and re-read LotR and Silmarillion as well as other of his Middle Earth books.
I love this show.
Yes, there are changes to the storyline amd timeline, but not to the broad strokes.
They've done a phenomenal job with back stories that explain the characters' motivations for what we already know that they do/will do. I don't love Galadriel in Season 1, but that is a minor discordant note. Durin, his wife, Sauron, Pharazon, Elrond, Elendil, and Miriel are very nicely characterized.
Visually, the show is gorgeous. In contrast to the muted colors of an older Middle Earth in Jackson's films, the rich royal colors make the setting feel like an earlier time.
As for the pacing, it's a bit of a slow burn in the first season, but if you've READ Tolkien . . . well, it's a very authentic feel.
All in all, it's a beautiful, complex weaving of multiple storylines worthy of the source material (the indices in RotK, NOT the Silmarillion).