Yes, absolutely, Brutus was most definitely an honorable man. Think about his initial resistance to Cassius' advances: he asks what sort of dangerous path he is being led down. Brutus has no personal grudge against Caesar; in fact, he is the last to stab him because he has the least amount of personal hatred toward him. While Cassius, Trebonius, Casca ("speak, hands for me!") and others fly into him with rage, Brutus simply waits until the end, and without emotion, does what he feels is necessary to protect the Roman state.
Also, one thing that I think truly separates Brutus from the other conspirators is his sense of conscience and justice. While Brutus has the least amount of blame for the murder (having done it for the good of his country, rather than out of personal jealousy as did Cassius), he sees Caesar's ghost several times, which is a sure sign of his sense of guilt.
This also points to Brutus' sense of personal responsibility. He never felt right about his decision to kill Caesar afterwards; and when he realized that he had indeed acted inappropriately, he used the knife that he plunged into Caesar to take his own life, out of a sense of obligation. He did what others were unwilling to do: when he realized he could do no better than his predecessor, and that he was actually harming his countrymen through his rule, he removed himself from power.