Well, a few months have passed and it looks like reaction to House of Dragons has been mediocre but not terrible. I watched it because I'm a long-time George R.R. Martin fan, which makes me probably not the audience HBO is particularly targeting, but...
My reaction to the series, much as to the written work it's based on, is ... meh, it's okay.
I'm a fan of world building in science fiction and fantasy. Pulling it off convincingly is impressive, and Martin certainly knows how to do that.
But the prequel to A Song of Ice and Fire was always something of an indulgent exercise in world building designed to prop up the main story and appeal to hardcore fans. I'm sure it must have been fun to write, and some people have fun reading it and now watching it.
But it's ... well, we already know what's going to happen, don't we? Not the specifics, but certainly the broad strokes.
Is an element of fantastical mystery missing? Magic, in a literary sense possibly, is missing. I watched the whole first season, though. So maybe they're doing something right.
But I'm nowhere near captivated like I was with the original.