It all depends on how much money your making. The only extra fees for a offshore bank usage is the wire fees are higher. Instead of a wire costing $25 to $30 and offshore wire is approximately double at $50-$60 depending on the bank. So if you have to move money around a lot its not a good idea unless you are talking about serious dollars. In which case I want to know your secret. My adsense account makes about $5 per day
Anyway back to your question. How were you planning to get paid by adsense? If by check, that will be painful. Cashing a check offshore take 2-3 months to clear and there are additional fees. So it all comes down to how much money you will be processing. A better way to operate would be to get your check onshore and pay a royalty to the offshore company. Read here:

Pros- Not as many as you may believe. If you’re a USA citizen the IRS will be on your books like a beaver on a log!
Cons- Not insured and can cost an arm and a leg. Too many problems with transfers//fees/ exchange rates, etc. Asset protection? That’s a fluke.