Decoupage’s review published on Letterboxd:
The non-canon filler movie. Not very good, often quite boring, almost insulting how lazy the story was written. Characters exist just to help the protagonists (whom they've never met) and then quietly die with a smile on their face. Kikyo aids the villains for no reason, but then she shows up to help Inuyasha one time, then just quits the movie because she says he can do the rest on his own. The main villain could kill anyone whenever she wants but she doesn't because "reasons". Come and fight me at my castle instead!
There's also the problem that Kagome was kidnapped and Inuyasha had to come rescue her yet again. That's just an aggravating plot device recycled from the first movie. Castle Beyond the Looking Glass came out around the same time as Episode 98: Kikyo and Kagome Alone in the Cave. That was one of the best episodes in the entire anime series, when Kagome showed her true strength and developed as a character without Inuyasha's help.
This second Inuyasha film even managed to mess up the one thing it had going for it, which was the romantic progressions at the end. If you manage to watch through the horrible fan service credits that include characters that didn't even appear, then you get to see everyone turn the kisses into just another childish, petulant joke.