The most interesting element to come out of this film is a Japanese director taking on a French speaking film. Certainly an unexpected turn for Hirokazu Koreeda, director of the highly regarded Shoplifters, but there's nothing especially stimulating about the Truth. It has good performances, it's shot nicely and yes, it has things to say about stardom and it's impact on family, but not much else to elevate it from just being ok.
The only strong reaction I had for this film would be my complete destestment of the main character Fabienne played by Catherine Deneuve. She is an absolutely repulsive person who cares purely about her glory and her disappearing stardom. You see, Fabienne was a huge French star who has gone the way of the dinosaur and feels lost in a world that seems to be moving on from her. While a lot of material to work with here, Fabienne does not make it easy to like or even relate to her. Which is a problem when you can't quite convince yourself why her poor daughter played by Juliette Binoche is at her side for the runtime. She is a horrible person to be with and it doesn't quite make for an enjoyable experience when you detest her the entire film.
There are some generally nice moments sprinkled in the film especially the ones involving Fabienne's grand daughter who shines a light in all the falsity and horribleness of the actor world. Ethan Hawke is also a very charming presence in the film playing the wannabe actor/husband of Fabienne's daughter.
The film making scenes where it revolves around Fabienne starring in a science fiction film about an immortal young mother (Which has some thematic resemblance to Fabienne's real mother) are also well choreographed and generally interesting. The rest however sort of meanders on, not really finding any strong footing to land on. It purely floats around a character who isn't particularly likeable, sympathetic or for that matter, interesting.
I can't say it's bad. If you are looking for a sort of reflective and quiet look at a celebrity struggling to be still relevant and the dramas she puts her family in as a result, then sure it will pass the time well. I can't say it's going to be remembered long after though. More likely you'll remember how much you wanted Fabienne to receive punishment for being such a horrible person.