My wife and I have just finished watching the full series and I have to say that we were gripped from the very start.
Whoever cast Sophie as Joan certainly knew their job and knew it well. As a matter of fact, the whole cast were brilliant and I don't think they could have picked anyone better.
After watching Sophie in the Game of thrones, I was surprised she did so well for her first major casting. But after this performance, I can honestly say that I would go as far as saying that she truly has to be one of the best actresses in the UK at the moment.
Also, I have to give credit to the actor that played Boisie (His name slips me sorry). Again, he gave a superb performance and his and Sophie's on screen chemistry was nothing short of awesome.
All in all, I loved it and it makes me want a season two. Fingers crossed.