Far more durable and comfortable than BBO. Outstanding tension maintenance, comparable to natural gut.
Most attractive aspect to me is its control. NOTHING else comes close when used as a cross with gut mains.
I have two frames strung with VS/4G and the third is used to compare other poly crosses. All frames are matched for weight, balance, and SW.
Repeatedly I've tried a different cross, many with which I was pleased prior to 4G's release. In every case I go right back to 4G. Nothing else inspires such confidence in my strokes.
It's definitely low powered, especially as it ages. Even then it still retains some pop and isn't uncomfortable.
It lacks the spin potential of other polys which is the one reason I'm willing to keep dorking around with other polys. And yet as a cross with gut mains I still get excellent spin.
There has been much hype around 4G, especially the "good as gold" tag line. In this case, it really is accurate imo. It's NOT for everyone. If you prefer lower power and tons of control you'll fall in love with it. If you want power and maybe more spin, you might be disappointed.
For me, it's my Broke Back String. "I just can't quit it!"