TW's summary really does "sum it up" IMO-----
"Gosen Polylon is a good old-fashioned polyester string. Unlike the emerging crop of high tech co-polys, it isn't loaded with extravagant chemical additives. Nor does it have a cadre of professional players who swear by it. What it does have, according to our playtesters, is remarkable control, especially at the highest swing speeds. It also has tremendous spin potential. This is partly because Polylon's response is so predictable and low powered that it enables big hitters to attack the ball at extreme upward angles. As for comfort, this string surprised our team by offering a feel commonly found in more elastic (and more expensive) co-polys. Of course this doesn't mean that Polylon is for everybody. It's a firm string designed for advanced players. Ultimately, though, once you factor in the price, which is less than a couple of vibration dampeners, Gosen Polylon is one of the all time best options for big hitters on a budget."