I didn't see the witness, how was he? Before I came here I glanced at Diana Tennis' Twitter and saw she called him an "emo guy" or "emo vet" (and got killed for it before she said she'd been only kidding).
To me, he came of as sincere. Emotional in that he doesn't like to hear people screaming in extremis, O'Mara said that listening to the 911 call was sort of a "confronting your demons" experience. The witness teared up more than any other on hearing the screams, which is probably the reason Tennis made her remark.
Other than that, he seemed very level, very respectful of the court and de la Rionda, didn't hedge or hesitate his answers, admitted the help he'd given to Zimmerman in the way of money and clothing. Not sure how believable the jury will take his statement that he would not lie for his good friend, Zimmerman, but I found it to be credible.