My son downloaded The Game of Thrones for me onto my Kindle. It has taken me many months to read the first four books on my Kindle, but it has been an enjoyable journey. The only thing is, as a working adult, I usually start reading in preparation for going to sleep. Some nights I only made it through a few pages. Other nights I stayed up well past midnight as I could not put it down. I have not seen any of the t.v. episodes so I cannot compare them for you.
The genre is high Fantasy. Mostly it seems medieval, but throw in a sorceress, dragons, the undead wights, and even some mastodons. There is a vast array of characters but the author lists all the families and characters at the end of each book. The characters develop throughout so early on Danerys was my favorite character. As time went on Brienne and Arya became more interesting to me. The book alternates between Westeros, the Western Kingdoms, The Wall (between Westeros and the wildlings), and the East. There are warring kingdoms, a continuous shifting of alliances and succession of rulers.
There are references to brothels, prostitutes, rapes, and some graphic sex scenes so I would place the cutoff as not before high school. There is also torture, executions, hung bodies pecked at by crows, and similar that you would expect in a medieval society. I really enjoyed the series, but it ended rather abruptly in Westeros. Now I have to look for the sequel which tells more of the characters in the East. The author admits the last book was getting too long so he decided to concentrate on the Western characters and come back with a new book called A Dance with Dragons. http://www.amazon.com/Dance-Dragons-Song-Fire-ebook/dp/B003YL4LYI/ref=sr_1_1?s=digital-text&ie=UTF8&qid=1367811602&sr=1-1&keywords=dance+of+dragons
Martin, George. Game of Thrones. 4 bundle Kindle edition. http://www.amazon.com/Game-Thrones-4-Book-Bundle-ebook/dp/B004JN1D2I/ref=sr_1_2?s=digital-text&ie=UTF8&qid=1367810615&sr=1-2&keywords=a+game+of+thrones