The biggest factor for you is probably going to be the loan terms and total costs. Since you will be living in one side of the place, it might not cash flow as well as if both sides are rented, but you will be saving on your own housing costs. You need to break down the numbers as far as what the cost per month is (taxes, insurance, mortgage, utilities, trash pickup etc.) Ideally the rent from your tenant would cover all of these expenses and then some. You will need to have a chunk of cash available for major repairs (roof, furnace, siding etc) because those things will fail at some point.
An example:
Mortgage (30 year fixed at 5% with 20% down) = $515
Taxes = 108
insurance = 100
misc = 100
Tot= $803
Rent = $700
Net $-103
This might look bad but if you consider the $103 to be your own rent then it starts to look pretty good. These are ballpark numbers and you'd have to have better estimates before making a decision. There are also lots of advantages to being owner occupied in terms of interest rates and tax savings.
All in all it's probably not a bad deal, just do your due diligence before signing anything.