As long as the third season holds the same quality, this series will be remember as one of the best sci-fi series ever made. The reason that it isn't already is probably because Apple TV isn't as avalible in many regions. I had hardly heard of the series and nobody I know has Apple TV. But more people around me are talking about this series and how great it is. I think it's popularity is growing. I fell in love from ep. 1!
It looks gorgeous, most of the acting is great, the story engrossing. Is it = the books? No it's modernized + rewritten masterfully. Prepare for a complex plot, and see it! You wont regret it, but don't compare it to the books. It's it's own thing, inspired by the books but reworked from the buttom up for a modern audience.
The sci-fi jargon and interesting ideas are executed brilliantly, which somewhat clashes with later episodes which introduces concepts that lean more toward fantasy. I won't deduct points for this, it's just my personal preference that I dislike "science fantasy". Apart from that I have no negative comments, the story is deep and captivating. Don't expect light fun or non-stop action, prepare for some philosophical and complex plot ideas that are explored quite deeply and several plots that often run completely paralell. If you're prepared for that and don't mind these things, than you will surely not be dissapointed!