I've played it. I've got it beaten at less than 20 game hours. Not 100% completion but I am not a completionist. I liked it. It plays a lot like Saints Row 3 which I liked a lot as well. The grappling device is a creative and unique mechanic barring every Spiderman game ever. And being a true American, I thoroughly love blowing up commies, fascists, and pretty much everyone who isn't American.
I've only got three criticisms on this game. It seemed pretty short to me. That it's not mandatory to capture or even discover every base probably had a lot to do with that. There's a whole lot of game that didn't get played. The grappling device, though a sure benefit, isn't like a... you know how superheroes in comic books have special abilities that are absolutely essential to killing their enemies? The grappling device would have been a great one of those, but instead it was my primary means of transportation. Still important, just not epic. Last was the ending, I was very let down by the ending. The ending itself wasn't bad, I was just expecting a whole lot more. I think this is because of how the game felt a lot like SR3 to me - the endings in SR3 were excellent and I guess I was hoping for something just as epic in JC2. Hyping myself up is my fault though.
That notwithstanding, it's a good game and I did enjoy it quite a bit.