I'm a well read grad student who's bluntly honest about all things, although I try to be most honest about myself.
It added to the mythology of the world, it explained Ultimate Thor's origins and why he was so against joining the Ultimates in the first place, it has a nod to Dr. Blake - which threw me for a loop and was amazing when they revealed who he really was. But most importantly, it delved into Thor's character, his self-doubt, how and why he overcomes that self-doubt, and I felt I got to know him far better as a character. It made him more full, more alive, in my eyes.
It was compulsive reading, too, and I found myself unable to stop, needing to know what happened next. The story was more of an origin type, so I would argue a little less focus on the action and a little more focus on the characters. There were battles a-plenty, just leaving time to dig into the characters - Thor, and Loki for the most part - in between. Very satisfying!
Scribd is going to be dangerous for me with so much of the Ultimate universe now a part of their library...