Plus, with the capability of going Warp 9.965, it could easily get away if needed and fly circles 'round the destroyer. And they could just beam an away team straight to the destroyer's bridge to phaser some ass...
What about TIE bombers? Several bombing runs combined with squads of Fighters swarming the Enterprise? Given I don't know the firepower it has but I don't think it could handle twenty TIE fighters and the Star Destroyer's batteries all at once.
But are the size differences between the two? Since I know more about Wars then Trek, is the the Enterprise the size of a Corellian Corvette? Or a Mon Calamari Cruiser?