It sounds like he has an interesting take on Richard, for sure. (OTOH, I read The Daughter of Time at an impressionable age and then made the mistake of actually doing the research, so probably it's just as well I can't see it--I always mumble angrily throughout Shakespeare's Richard III!)
According to the Daily Mail (and a few other sites that wouldn't show their articles to non-subscribers), there is some disgruntlement at the mid-scene applause Martin's fans are bringing to the show. I understand their enthusiasm, but that could be annoying if you're trying to watch the play. (It's not a musical, where they expect applause mid-scene, after all.
ETA: One London Theater Tickets, the director of Richard III says the whole thing is a non-issue, it only happened once, between scenes, in the first preview. (Who knows, I certainly couldn't afford tickets even were I in London!)
And there's another review of Freeman in Fargo on Yahoo TV UK.