Unity 4.3 features enhancements and new additionas specific to 2D that should make it much easier to do 2D games in it.
http://www.youtube.com/watch?v=MoZlMGU99qk
Still doesn't compare to the developement speed of C2. Yes I'm glad they are adding support for 2D. Which is awesome. I think Unity is still viable platform due to it's exporting.
However. Everything about gameplay is still line by line hand written. There is still no robust API to support 2d game logic. Collisions, movement, reactions, determination of landed, in air, speeds, states and everything is still line by line coded in JS or C#.
Where C2 shines is that it already does soooooooooo much with it's Platform behaviour. It handles jump thru, collision, vectors, events so on. Where a handful of lines still needed to be coded in Unity. Would equal 1 Event/Action in C2. And on top. There is no risk of syntax error and logic flow is easier to follow.
yes though. Those who want to use Unity will be far better off now than before. Thanks for brining the attention to unity 4.3 2D features :)