I like the concept, it's a very interesting take on "control 2 characters". but I have to agree with Brohmyr's and Zettabit's points. and if you don't mind, one more suggestion from me: I think the game needs some kind of timer or any other visual representation of switching between the characters. and if there's a timer that player can see, you'll be able to play around with it to create more challenges, make it longer or shorter, add an ability to change the timing, etc.
anyway, few more steps, some polishing, and it would make a great game. keep it up!