Не лепо ли ны бяшет, братие, начяти старыми словесы трудных повестий о полку Игореве, Игоря Святославлича!

and

Не начать ли нам, братья, по-стародавнему скорбную повесть о походе Игоревом, Игоря Святославича!

not exact literal translation from old Slavic to modern russian, but if the old Slavic text of "Слово о Полку Игореве" is understandable for you and you can describe it in modern russian, you can IMHO consider yourself an expert. But if you don't understand it at all it's still worth reading just to listen the way in sounds.