Horatio's Words, Disapprovings or No.

It sounds more like Horatio is in awe of what Hamlet has done. He is impressed that Hamlet was able to escape from pirates and trick England into killing his captors. In line forty, he says that his writing a note was good, however, this is before Hamlet tells him what was in the note. The picture I visualize is him nodding his head with wide open eyes. His short responses could either mean he wants Hamlet to keep talking, or it could mean that he is not impressed and is disappointed in him.