imo it's not that great. The missions are very linear, and I've always hated the 'sneak,kill,hide' kind of missions, especially when there's no saving system.
What multiwindow? Every missions starts with multiple windows which breakout when you start moving, there's no multiwindow. Or do you mean the stupid screenfilling cartoons when you shoot someone in vital area?
I shuttered with fear when the first mission with objective 'XXX must not die' came up, every game that has that kind of objective has had it's AI suck. The one you should protect, always felt compelled to run in the middle of bulletrain - instead of waiting for me to cleanup. Gladly they didn't