I watched it. It was okay. I can't recommend it, though.
Kit Harrington didn't play Guy Fawkes. He played Robert Catesby.
All the nudity takes place in the execution scene. Elizabeth Catesby is sentenced to death along with a young priest. She is stripped and crushed with stones. The nudity is pretty unnecessary and could have been avoided with better camera angles. The young priest is disemboweled and drawn and quartered. It's graphic but it is historically accurate.
The show was sympathetic to Catholics up until Robert visits Spain. There it showed the Spanish burning Jews at the stake. It tried to equate Catholic suffering in England to the suffering of Jews under the inquisition.
Some other takeaways:
It hinted that King James I was a homosexual. He's always in the company of a young man.
It hinted that one of the Catholic priest was in a relationship with Anne Vaux. It wasn't a sexual relationship but a relationship of the heart.
The Spanish were secretly involved in stopping the plot by getting a priest go give up the location. The Spanish do it to secure their peace treaty.
King James I is manipulated by Lord Robert Cecil and is main driving force behind the Catholic persecution.
The English aren't portrayed as sympathetic in the mini-series.