Nostalgia armor will shield this show from criticism
McGregor's take on Obi Wan is beloved. When people talk about Obi Wan, they talk about both him and Guinness. It's very rare that someone playing a character someone else is responsible for bringing to life is liked this much. Hell, it's arguable that people think of him more when thinking of Obi Wan at this point.
Couple that with the fact we're going through this bizarre prequel lovefest driven by Lucas Cultists and I think people will not criticize this show much. Hayden Christensen sucked in the prequels, but everyone is ecstatic he's back. Please.
Now that's not to say this show can't be good. I think the trailer looks well-made.I think there's a good chance this show will be good. But I think people will ignore any flaws or shortcomings based on "fondness" for the prequels and McGregor.