This old house is fine. It's as comfortable as an old shoe.That's a great tradition—comfortable as an old shoe.
(as) comfortable as an old shoe
Very familiar or comfortable, especially in an agreeably unpretentious or unrestrained manner. This car may have seen better years, but it's still comfortable as an old shoe to drive around in.
*comfortable as an old shoe
Cliché very comfortable; very comforting and familiar. (*Also: as ~.) My old house may seem small to you, but I think it's cozy. It's as comfortable as an old shoe.