Ostensibly it offers us "cheaper products" in an ever increasingly connected world. However, it has the inadvertent effect of broadening the labor pool, driving down American wages, and eliminating U.S. jobs.
If you could pay an American worker 13 dollars an hour or an Indonesian .40 cents per DAY, which would you choose?
Of course, you have to add shipping costs, but those are stable and aren't as much as you'd imagine, which is why "outsourcing" the manufacturing of products is advantageous. Tariffs are supposed to equal the playing field, but we rarely see those, and when we do, they don't have 'teeth' to effect their aim.
In short, it's a BAD DEAL for American workers, a WASH for American consumers, and a GOOD DEAL for corporate bottom lines and shareholders. Those three facts are indisputable. What is disputable is whether or not we should, from a normative sense, desire and implement such a deal. I vote not no, but hell no.