Yes, this is the best episode of the series so far. But, I can't help but feel that Trey and Matt could have done a much better job of lampooning GOT 5 or 10 years ago. I like the recurring "betrayal garden" gag, but there are scenes that immediately spring to mind when you try to imagine what would happen if South park did a GOT episode, and many are missing. For example, when Cartman was overseeing the boys practicing with wooden swords, I thought, "It would be so awesome right now if Cartman used some of Syrio Forels lines" . And that has happened quite a few times in this trilogy so far. Even the gag about the authors obsession with gay wiener isn't especially funny because it's just not true. I've counted! The gay wiener count is exactly 0. I didn't count straight wiener, but - off the top of my head, it's like 3 or 4.
This episode would get a 10 if I were only comparing it to the rest of this season. Overall it gets an 8. But if it were in season 8 or 10 for example, I'd rate it a 6.