Reserved is probably a good word to use, and not only for Henry Cavill, but this film is a 19th Century period piece which the British usually do very well, with a lot of attention to detail, and this is the case for Enola Holmes as well.
This Netflix film is obviously a career promotion for Millie Bobby Brown, you also can't help thinking that Cavill must have had this Netflix title as a clause in his contract too, not knowing anything about the Enola Holmes book series I can't interpret what version of Sherlock Holmes Cavill was trying to play, but it didn't really matter as the movies main focus is pretty much on Millie Bobby Brown who has always looked more mature than her age even in Stranger Things, what Netflix plans to do in the future to keep Millie under their creative control will be interesting.
Enola Holmes does look to have a prospective franchise sticker attached to it, Netflix like these sort of star studded productions to bolster its subscription quotas from time to time, if another movie is made the franchise just needs to continue were it left off, Enola Holmes was entertaining enough though it did feel like some scenes needed a bit more acting charisma from the films well known supporting cast on occasion.
My rating is 7 out of 10 mostly for Millie Bobby Brown and films production.