There is definitely a tragic element in the character of Shylock. The rampant anti-semitism of the age provoked lines like "hath a Jew not eyes...If you prick us do we not bleed?" (3.1.59-70) but for me, Shylock revokes my sympathies when his daughter elopes and steals his money. He rants, claiming that he wishes his daughter was "dead at my foot / Jewels in her ears! / Would she were hears'd at / My foot and my ducats in her coffin!" (3.1.88-90). In my opinion, this sort of outburst reinforces the stereotype of Jews as greedy and murderous.
As for comic element, sometimes Shylock is laughable in his efforts to keep his money and his daughter in check, but overall I see him as a tragic figure beset by the climate of his time and his overall personality shortcomings.