Yeah, I got it in yesterday and went out and played a round immediately after work. Great bag. I immediately liked it more than the commander.
The commander is a great bag, it's light weight, the main compartment holds more and isn't nearly as tight when inserting / removing discs. That said, I really didn't like the elastic putter pockets on the commander, and it missed having smaller divider pockets within the side pockets of the bag. I don't like it when my cell phone, wallet, bug spray, snacks, keys, and everything else is just rattling around in 1 big pocket.
The ST3 is bigger, heavier, but more comfortable at the same time. The padding is great and feels quality. The level of refinement is there (lots of extra pocket room, divider pockets within the large side pockets, included rain fly, etc.
Really, the only gripe with the ST3 is that it comes a little "tight" and stiff, but that will break in with time. It's a fantastic bag, which I knew it would be since I own a Mojo and absolutely loved it for the past 6 or so years.