Glorious. Truly a masterpiece. The acting, the writing, the soundtrack, the cinematography. A wonderful pacifist piece that defies ignorance, blind faith, gender roles, and sexuality. It brings an unashamed perspective on good versus evil and their place in religion. Written for people who can't help but ask questions and be existential.
Since it's not entirely faithful to the source material, I would recommend reading the book if you haven't already, regardless of if you do so before or after watching the show. It adds SO much to the story and furthers the world through another medium. However, Michael Sheen and David Tennant have so much chemistry and bring so much life to their roles, that one would truly think they've been (boy)friends for six thousand years.
My only critic would be that out of my own personal preference, I found some of the side characters less interesting compared to the protagonists, and could have done without a few of them. However, this is purely subjective, and not enough to detract from my overall opinion of the show.
Reminiscent of the wit and humor of Monty Python and an inventive aesthetic like Series of Unfortunate Events. The humor is striking, an instant dose of serotonin coupled with dark and insightful subject matter.
Fantastically ineffable.