Phenylacetaldehyde dehydrogenase that catalyzes the last step in the aerobic styrene degradation pathway by mediating oxidation of phenylacetaldehyde to phenylacetic acid. 2-phenylacetaldehyde + H2O + NAD(+) = 2-phenylacetate + 2 H(+) + NADH Aromatic compound metabolism. Belongs to the aldehyde dehydrogenase family.