Richard Frye wrote this book for the non-academic public. That is, it is written for the laymen. It is a translation of the largest piece of the Risala which had been preserved at Meshhed. He filled out his translation with a bit of history of the time in which Ibn Fadlan made his journey, c. 922 A.D.. I am not sure how best to refer to the Arab author since Ibn means 'son of', so perhaps Ahmad would do.
Ahmad took a long way around to visit the Bulghar king at Kazan because the Khazars, whose land he would have to cross, were hostile to the Caliph at Baghdad, Ahmad's master. It is an interesting look at a culture and history that is largely unknown to me. It is not too long or filled with obscure details that only a scholar would love. It contains some maps and illustrations, which I love. All in all, it is a good book. Two thumbs up.
If you are curious about the Ahmad's observations on the Rus, you will need to look further because Frye did not comment much on them. He stated there were many scholarly articles already on the subject.