Buying Half a Duplex

You bet there are! Some of them are the same problems you'd have if you bought a single house with an unrelated partner. For starters, who decides if the place needs a new roof? What if your co-owner doesn't have the money to pay for it? What if your co-owner can't meet his or her mortgage payments? For that matter, are you planning on paying cash, or do you know of some lender who'll take a mortgage on half a house? Are you going to for a cooperative of a condominium organization, are you going to sign a written partnership agreement?

I'm afraid you'll get my standard advice -- talk with a lawyer before you do anything.