IGN just shared a new still and their interview with Henry after visiting the
 U.N.C.L.E. set, and it's filled with AWESOME details. Here are the highlights, but 
make sure to catch it all on their site(tomorrow).
  
The Actors Didn’t Know the TV Series
Henry Cavill: I didn’t ever watch it. It was before my time and what   attracted me was Guy [Ritchie]. He’s a great director and the story was   very cool and I thought if anyone can make this even cooler, it’s Guy   and so that was the selling point for me.
 Tom Cruise Was Supposed to Star
Wigram: We were going to do it with Tom Cruise and for various   reasons that didn’t work out. There was a moment just after that when we   had been considering Henry for Kuryakin, as well as Armie, and we said  –  you know what? We talked about Henry at the beginning for Solo – why   don’t we go back to that idea and the studio said ‘You know what?  That’s  a great idea!'
We chose them because honestly we felt they were  among the best young  actors of their generation. We feel that – and the  girls as well – we  feel that we have the next crop. The next generation  of movie stars.  We’ve been fans of Henry since The Tudors where I  thought he stole a  lot of the scenes he was in, and we’ve been fans of  Armie since The  Social Network.
 
 Much is Staying the Same
Wigram: The personalities of Solo and Kuryakin are inspired by the show, clearly.
Cavill:  My character is not a born CIA man. He was very much into the  black  market before that and got blackmailed into the CIA… he has  learned some  skills, but he’s not sort of born and bred by any means.
Hammer:  Illya is a bit different and that kind of creates a duo dynamic  between  the two characters. He’s a born and bred spy. He is a KGB  agent and  that’s the only thing that’s important to him and that’s  pretty much all  his life is about and that does create a little bit of  friction between  the two of them.
Cavill: I’m more anti-establishment and sort of more self-serving, I would say, whereas Armie…
Hammer:  …he’s a hardcore red communist, you know? It’s all about the   establishment and it’s all about the aberration of sort of the sense of   American entitlement, you know? So there’s a lot of that. It’s a very   different way that we both approach our jobs and at different times it   definitely bugs both of our characters… they’re just opposite ends of   the spectrum really.
 The Script is Flexible
Cavill: We come in every morning, we run a scene, and when we’re in   the room it’s a lot easier to work out which dialogue works better and   so every morning, you know your lines, but expect them to change or be   prepared for any kind of change. Some days they stay exactly as they   are, and other days they change completely, and that’s quite refreshing.   I quite like it, because there’s no opportunity for the scene to get   too stale before you actually perform it – if you over-rehearse it for   example. So you get in there and you do it and it feels fresh and very   new and of the moment when you’re shooting it.
Armie Hammer is the Ultimate Action Star
Cavill: There’s a lot of stunt work and I’ll pick on Armie,  because I  know he won’t do it himself. He’s been doing incredible  motorbike stuff  and incredible boat stuff as well. I had no idea he was  so talented  doing these things, but his stunt double, poor guy, hardly  gets a  chance to do anything, because he’s out there doing it all by  himself.
Hugh Grant Might be the Film’s Secret Weapon
Wigram: The character of Waverly [the chief of U.N.C.L.E.] is played   by Hugh Grant, who does a brilliant job. He’s an example of an actor  who  is absolutely brilliant… you’ll see some of the touches in his  dialogue  are brought by him. He’s just very, very clever. He’s much  better at  dialogue than I am, that’s for sure.
Cavill: He’s brought Hugh Grant to proceedings.
Hammer: It’s a trump card.