Now, I am writing as a person who has not played any Warcraft game or World of Warcraft and who hasn't read any of the Warcraft novels, yet I picked up this manga because I liked the covers and the artwork looked okay. Not a very good reason on my part there, but I was overall satisfied with this 3 volume manga.
-- Story --
The story is okay, but it feels rushed. In the first part of the first volume the pace is okay, but then things just go like a boulder downhill. There are moments when the pace goes slower in the second volume but the third one is rush rush rush. There is a natural twist to the story that we find out about, that isn't too great. The story is simple, confusing at times with lots of gaps and inconsistencies. I believe most of this is because of the shortness of the manga, if it would have been longer the plot might have been better expanded and created a much more interesting story.
-- Art --
One of the main good points of the manga is the art. It is clear and portrays expressions well. It is also incredibly detailed. The scenes with big sceneries, mountains, castles or plains are awesome!
-- Characters --
The characters lack in depth. It's very hard to have a favorite character when you barely get to know much about them. Many of them have some back stories present, through flashbacks, but the actual time to develop a character well is not present. It's the main characters that don't get enough interaction and character development. On the other hand the palette of characters is diverse but easy enough to remember and bring a value of entertainment to the plot.
-- Enjoyment --
Warcraft: The Sunwell Trilogy is enjoyable. Battles, dragons, evil mages, medieval fantasy most things to make an enjoyable story. If you ignore the slight cliche and lack of depth it makes for a good one afternoon reading.