Within the opening 10 minutes of this film many things become clear. Firstly, while this has been mooted for years as a possible oscar-vehicle for Julianne Moore, that is almost certainly not going to materialise due to the tone of the film, which is very trashy. It begins like an ode to a Joan Crawford-type performance, it's very overtly gay in tone and as such neither subtlety or restraint is expected to follow. The film goes above and beyond that.
The plot is basically chronicling the heirs to the Bakerlite fortune in their lives across Europe. The husband (Stephen Dillane, almost unrecognisable with a moustache) has a tempestuous relationship with his wife (Moore) and the son (Eddie Redmayne, who did a very nice little job in The Other Boleyn Girl) who as such has almost no chance at being normal. Instead it turns out he likes boys, much to the tacit chagrin of daddy, who merely likes taking Julianne in the rear every now and then. Did I say this was trashy? Oh yes. Well, I think we need a new word because it doesn't quite cover it - the countless "scenes" be it naked locker-room tomfoolery, multiple gay scenes, threesomes, etc. are just so endlessly tiresome and so overtly exploitative of the salacious subject matter it's almost impossible to take seriously.
That said, the couple (I would say leads, but the further the film goes the more it focuses on Julianne's relationship with her son) both turn in excellent performances. Dillane always has a natural subtlety (well, ok, maybe not in King Arthur, allow me to rephrase 
- Dillane *at his best*...) and brilliantly holds everything back. Moore may well be my favourite actress working at the moment and here she has moments where she shows why - she has certain scenes where what she's being asked to portray is so perfectly realised, yet she cannot escape that the tone of the movie is making it slightly ridiculous for being so camp and unrestrained and dependent on the subject matter to retain interest.
The latter point is the film's downfall, the *best* (oh what a relative term that is in this case) drawn relationship is probably Julie and Stephen, but that's sketchy (and I'm actually being kind in that evaluation) and not exactly something to be overcome with wild joy about ... when the film increasingly becomes more about Julie and her son. And you can guess where this thing is going from the relentless trashiness, oh, it's such a shame because the acting is very honestly done and deserves so much better and even a supporting cast including Belén Rueda have very little to do.
Is it worth it? I don't know, probably not, it's pretty far from being remotely a good film and has so much wrong with it and so much that misfires it's actually almost impressive (and they made a fully naked Elena Anaya somehow unsexy, you really are excelling yourselves boys...). Julie and Stephen will retain an interest, but try as they might (and they try mightily) I don't think they can save it.