I liked her in Mission Impossible V but I agree with Ace on this one, I mean she wasn't spectacular or anything either. We shall see though I mean she definitely has an interesting look to her.
Her character was just two-dimensional and abysmal, and Blue Is The Warmest Color was a three hour, coming of age/lesbian film that was horribly undermined by Abdellatif Kechiche's insistence on unnecessary, graphic sex scenes. TL;DR, films was meh. Interesting look to her, yes, and I applaud EON for going with someone relatively unknown to the basic movie goers eyes, but I'm not holding my breath out for her.
I agree with you on this: her role in "Mission: Impossible IV" was underwritten, and "Blue..." was a massively overhyped tv movie spiced up with unnecessary porn. Still, Sedoux is a very capable actress and has given amazing performances in many French films. She will bring something fresh and unusual to a Bond film if given a decent role.
Blue Is The Warmest Color was an hour too long and horribly paced. It's a mildly interesting film, but the sex scenes are completely dragged out to the point of it being pornography. I also just remembered that the other film I saw her in was Inglourious Basterds. Other than that, I can't really comment on her other films and performances, respectively, but if you say she is capable and has given amazing performances, then I trust your word on it SAF.
She also played Isabella of Angoulême in the 2010 version of Robin Hood, but her role wasn't that big although she was still quite memorable.