The cast of original Peter Jackson's trilogy have been very vocal about Amazon's endeavor.
Actors usually have busy schedules, so they cannot be expected to immediately watch everything related to every franchise in which they have played.
But at least some of the actors who starred in Peter Jackson's The Lord of the Rings movies by now have watched The Lord of The Rings: The Rings of Power, the distant prequel to The Lord of The Rings, taking place thousands of year ago, during the Second Age of Middle-earth (though sharing a few characters, thanks to them being ).
Such as Billy Boyd, who played Pippin. He certainly has a lot to say about the series. And most of what he has to say is complementary.
"I have seen it. I liked it very much," Boyd said when asked about his reaction to The Rings of Power in an interview with SYFY WIRE. "I, as a fan of Tolkien, I loved seeing all these places again — some of them for the first time. You know, to see Khazad-dûm and Númenor and all these places. I think that gave me the most joy," he elaborated.
Boyd also commended positively on the structure of the series, something that most people criticize, and commented on the impressive variety of spectacular locations it presented on the screen:
"I think the way they jump from one place to another made it very watchable for me. I think, 'Oh, here we are in Númenor' and then it would jump to the caverns of Khazad-dûm. I loved that. And, seeing things like the rings for the first time — all of that is just really joyful for me. I loved it!"
Then again, Boyd was supportive of the Amazon's series before he could even look at the finished product and he's talking largely about scenic landscapes – which, it has to be admitted, are really beautiful, visual designers on these series drew no complaints from the audience – and new Middle-earth places to see.
Instead of, you know, starting with mentioning characters, plot or actor performances. This sounds a bit suspicious. Of course, we cannot read Boyd's mind, and hopefully he just liked the fresh illustrations for Middle-earth above all.