It's been a while, but for a time there I was doing four player games regularly. After getting a 2 player game in this evening and remembering those earlier sessions, I wanted to say something.
I mean, some of the ideas are good. The division of leaders and deck responsibility can be okay... but I think when it comes to delegating missions and action cards, it's flawed. In my case this was exasperated by having new players in both of those two player games, but I think as a whole it's not working.
Because for it to do so, you need to have both players compromise on what they want, and be familiar enough with the cards to know that certain leaders are best with some missions. It has to be enough that the General recognizes the Admiral really needs to have some good cards for his leaders, and "let" the Admiral take those mission cards. Why not just have the General assign all of those missions, since he has the hand of cards? That way he won't have to hand them over to the Admiral for the Admiral to look through and pick missions.
The only solution I've come up with so far is perhaps to create a new mission deck for each side, and then like how space/ground combat cards are divided, thematically divide the inside part by Admiral/General responsibility. That allows this new deck to be played combined, or separated for a better 4 player experience. Action cards could be similarly divided.