I think Jarrold missed the point of the novel...
...and that's largely why this film fails--not just as a remake, but as a film separate from anything else. For a long time I've been trying to figure out why this film felt a little shallow to me, given the amazing source material, the brilliant, spot-on acting, beautiful cinematography, and an elegant score. I think Jarrold was trying to appeal to a contemporary audience, but you can't remake Brideshead Revisited and treat religion like it's a byproduct. This was Waugh's first Catholic novel, he was a convert, and he is on record as saying that this book was about how God can pull people back to Him at any time. He actually likens it to an invisible thread, with God as the fisherman and the people as the fish. However you feel about religion, you can't deny that this in mind brings deeper meaning to the story. It fleshes it out, and without it, a lot of things don't make sense--number one being Charles' conversion to Catholicism, although this is presented more ambiguously in the film. Jarrold decided that the love story was more important, and even though it is significant, I think giving it the significance he did, that some of the deeper issues got lost.
I remember two things very clearly: I am a great sinner and Christ is a great Savior.