Hey,
You should give yourself/yourselves more credit. If this really is your first demo, I think it is extremely promising. And I'm saying this with nearly 10 years of C# experience and 3 years with Unity.
Some constructive criticism: (though you probably figured this out already) The controls for the green guy are a little sticky. What I mean by that when you let go of a direction, the character will continue for a little bit, and then come to a complete stop.
This is the classic 'unity' feel. There are two ways to fix this:
If you wrote your own controller, great! if this is the case, then I'm assuming you are using Input.GetAxis to check for user input. The unity documentation is a little lacking, as it doens't state that method can introduce very significant input lag if used incorrectly. GetAxis kind of 'ramps' up to it's 'on' value over the course of a few hundred milliseconds, and also ramps down back to nothing.
Even if you didn't make your own character controller, this is why the sticky feeling is there. When you let go of a key, it takes a while for the value to actually go back to 0. This would be problematic if for example you are doing: if(Input.GetAxis("Horizontal") > 0) for a right input check.
A simple fix is go either change this call to Input.GetAxisRaw (same thing, just doesn't do any of the ramping stuff) or (if you don't have access to the code) go into your input settings in the unity editor (Edit -> Project Settings -> Input -> horizontal and vertical), and mess with the 'gravity' and 'sensitivity' values. I don't really ever mess with these, but I think 0 for both will get rid of the ramping.
If you do this, all your future character controllers will feel very snappy and responsive.
Anyway, have a good one!