It doesn't look bad, but spin offs make me a bit lazy.
Maybe I'm wrong but I doubt that it will become what the main series was, since it had the A Song of Ice and Fire saga as its main guide. On the other hand, House of the Dragon, without being a bad book, is not that complete.
What I see lately is too many spin offs that want to continue taking advantage of past successes.
For me, for example, Vikings Valhalla was a bit disappointing. No character ever has the charisma of Ragnar, Lagertha, Floki, or Athelstan.
Something similar happens to me with the next series that is going to come out set in the world of The Lord of the Rings, the trailer looks very "white" and very politically correct, but pretty good CGI. I also don't know what it can contribute to the world of Tolkien without being based on a specific novel.
Anyway I will give House of the Dragon a chance, with low expectations, I hope it surprises me. Visually it is very good and if they have George R.R. Martin as a writer, I don't think he'll accept any nonsense.