Short answer: no. His magic is second only to Cloud - and Aeris, but she doesn't count - and he boasts a lot of MP. However, he is one of the frailest characters, his weapons don't damage much, and his Limit Break is unreliable. But there's a trick to make him one of, if not the, most vital party member. His last gun, Death Penalty, gets more robust with each enemy killed by it. In this way, you can make Vincent one of the strongest characters if you have the patience to grind it out.