I don't think it changes the Liberal narrative. They can harp about how it is a false surplus, jerry-rigged by the Conservatives for en election, and the investments are still needed after all these years, blah blah blah etc. (I think had the budget been in deficit it would have been harder for the Liberals, as they'd have to increase their borrowing.) This way they can promise more stuff.
It sorta helps the NDP, but only if they take the same tack re: phoney surplus. If the NDP tried to legitimize the suprlus then they have to take side with Harper and go at cross-purposes to their Conservative mismanagement messaging. You can't label Harper as mismanager when in deficit but ok when in surplus. It's bboth or none.