Yep sadly that it is. Worth playing again if you complete under 4 hours you get an unlock which doubles walking speed then complete again on Madhouse unlocks inf ammo! The game is designed to be completed about 3 or 4 times to unlock everything!
Starting to fancy playing it again even though I completed it twice. Might play it on the TV with a controller this time and just run through it fast to unlock all the cool stuff and then play the Madhouse mode which would be my 4th play then