It's hard to say. Rumor has it, and I say rumor because I've not seen any first hand evidence of this, that Agfa papers don't hold up well as they age. Storage conditions have a lot to do with how any sensitized materials age, so you never know. If it was stored in a cool, dry place, it might very well be good. Try it and see. If it works, then you've gotten yourself a bargain. If not, then nothing is lost anyway.
I have seen Polymax go bad. It developed the most unusual mottled fog I'd ever seen. Old papers that have gone bad are still useable if you fix them out, then wash and dry them. Coat them with your own emulsion for cyanotypes or other alternate processes.