If you are not carrying any 'true to the book' or '1981 TV version' baggage - and I read the former and then watched the original run of the latter with great pleasure - this is actually a very fine film. It is beautifully acted and filmed, with a strong, multi-layered plot, and watching it is a delight from beginning to end.
Brideshead: The Movie is heritage cinema at its most vacant, a Miramaxed 'periodpudding' for the US market (where it was, gratifyingly, shot down in flames). It's very pretty to look at, but any fan of the book or the original TV series (and I can’t think who else would want to see it) will find it a pointless, compromised yawn.
The indulgent languor of Granada's 1981 version was always going to be impossible in a two hour film, but it's not even a passable precis - it changes the story altogether. The main liberty is in sending Julia to Venice along with the boys; Sebastian sees Charles getting intimate with her by the canal, and becomes an alcoholic through sexual jealousy. This is just so wrong that I don't know where to begin. And there are incidental absurdities, where getting a nice location on screen trumps all veracity - at one point Charles and Lady Marchmain share a private tea in a vast college dining hall. Another key problem is the dialogue, which seems to think that it can improve on the book; the TV version captured much of Waugh's writing (often deferring to Jeremy Irons's lugubrious voiceover), but here Andrew Davies and his colleague just make up their own. Patrick Malahide does his best as Charles' father, but he just doesn't have the lines that made Gielgud's turn such a treat. Mr Samgrass gets about thirty seconds. As for the performances, most are serviceable, but Hayley Atwell is so bland as Julia that you can't understand Charles's interest. Ed Stoppard as Bridey and Jonathan Cake as Rex Mottram at least inject some colour into proceedings.