As a fan of history, I will say certain kings do get more of the spotlight than others. Henry VIII's father Henry VII won the right of the throne of England through conquest (though he did claim to be the rightful heir of the House of Lancaster during the War of the Roses) though his son became far more notable in history. You'd have to be asleep in history class to forget that Henry VIII changed the history of England by turning the country Protestant so he could divorce his first wife and later had rather ...interesting marriages later. While the House of Tudor include all monarchs from Henry VII to Elizabeth I, The Tudors TV series is really only about the the reign of King Henry VIII.
The show begins a good bit after the death of King Henry VII, as Henry VIII has already had his daughter Mary who is a few years old by the start of the show. While King Henry not being faithful to his wife Queen Catherine is no secret, he does seem to have a good relationship with her, and does care for his daughter Mary. We see Henry deal with foreign rulers like King Francis I of France and his nephew-in-law Charles V who is King of Spain and Holy Roman Emperor.
While Henry has had more women in his bed than many care to remember, one of them that catches his eye is Anne Boleyn. The young noblewoman pushes Henry away at first and this drives the young king crazy with love. Not long after, Henry starts to want to divorce Catherine, but her nephew being the most powerful man in Europe (and a man the Pope fears) makes this difficult. Cardinal Thomas Wolsey might be a man of God, but he has many enemies at court but he is close to the King. This makes him the chief defender of Henry's case to get the Pope to annul his marriage. However if King Henry doesn't get what he wants, things will not go well for a lot of people.
Overall I really liked The Tudors' first season. I'd say it's probably Showtime's closest thing to Game of Thrones. Fans of Game of Thrones will notice Natalie Dormer (who played Queen Margaery Tyrell) as Anne Boleyn and Ian McElhinney (who played Ser Barristan Selmy) as Pope Clement VII. I will say I did find it disappointing that they did distort history mainly with the combining of two of Henry's sisters into one character. Considering that one of those sisters lived on to produce a line leading to a future Stuart King of England, it's rather strange. I also thought of the movie The Other Boleyn Girl which I saw a few years ago, and I do think this was a better version of the story than that movie.