I saw a photo of Nathan from the other night and he appears to have lost his hair or shaved his head (he was wearing a hat) and looked like he lost a lot of weight. I certainly hope it is for a role he will be playing or he just wanted a change of appearance and not due to an illness.
The only review of a show that matters is your own.
I saw that too and was concerned but I thought I heard somewhere that he is doing it for a movie. (I think the O.J. Simpson TV miniseries) but I'm not 100% sure. If anyone can add, please do.
Which, as bfreak already correctly stated, is the O.J. Simpson murder trial miniseries (called "American Crime Story" as Terrence partially points out). He is not ill. Don't worry.