A great epic fantasy! I'm really enjoying this so far (6 episodes in). It is not flawless - some things are a little rushed, the characters behave at times in unbelievable (and idiotic) ways, but overall the story is gripping, the characters are interesting and mostly likeable, the world beautifully realised, the cinematography stunning, and the casting, on the whole, very good.
After doing a little review reading, I have come to the conclusion that all the one star reviews are from die-hard fans of the original books who feel that the TV version takes liberties and makes changes to the source material that are unacceptable. It also appears to have been another deliberate review-bomb campaign by such people before the second episode had even been released. It's a shame that they would want to discourage studios taking a punt on fantasy if you ask me, but such is web culture.
If you haven't read the series, and enjoy fantasy, there's a very good chance you'll love it. If you have read the series and have the mental capacity and willingness to separate the two experiences, you'll probably love it. If you are a die-hard fan of the books and can't tolerate any changes to the source material, do yourself a favour and skip it because you are unlikely to be satisfied here.
I am looking forward to the next two episodes, and hopefully many seasons to come!