Personatly i use Construct2 as it is made for 2D games (i've buy shiva3D and unity 3D too but for 3D).
The choice of HTML5 is not but very limiting the output potential on mobile (well futur is coming better and better but it's long too wait :p).
The only thing for me that construct 2 can do for doing better 2D is to have more easy way/plugin to add new modern 2D because actually thing like light,shadow,bump mapping ect... are hard to handle with it (and so easy with a 3D engine (but 2D setting it's worth)).
Actually Construct2 is working great and is easy to use and setup for basic 2D game on mobile.
For 2D PC game, it could be a great piece of software too but the actual design need to be tweaked to continue to be greatly integrated with the editor.
Construct2 need to keep is 2D only desing and the easy way it have draw to use.
It just have to extend this 2D to become more usefull for AAA 2D game on high machine.
ps: the sprite support was a really great choice of the extend for AAA game ;)