Yep...it is piston driven.
The recoil feels different than DI, not harder...just different.
You don't have to worry about keeping the BCG lubed, the lube doesn't burn off there. The bolt stays cool...the gas rings are out front at the piston, the piston gets pretty dang warm (much like the bolt on a DI gun).
I've fired appx. 2,000 rounds through the 516...I have no complaints, there is no sign of any damage from carrier tilt, its accurate, has never jammed with any ammo (factory and reloads), its well put together. It came with a cheap red dot sight thats usable but i wouldn't wanna take it into combat, it also came with a 3 point sling that has a pretty neat way of attaching to the rifle....my son says its better than they way they connect to issued rifles.
In the end...its just another AR15, a tad different...but still the same.