This Cocos2d-html5 alpha release use the HTML 5 Canvas 2d for rendering. It supports almost all features of 2D framework and 2.5D isometric framework , except some features that relies on 3d perspective (namely CCCamera). This even supported real time color tinting that will considered impossible for HTML Canvas 2d mode. There are features like Parallax background , Tile-map, Actions, Ease, Frame animation, Schedule , Labels , Keyboard Dispatcher , Scene Transition coming with this release.
So , this alpha release of Cocos2d-html5 offer many exciting features for developers which turn iPhone game development and other mobile game development into next level. As this is only alpha release there may be some bugs are found at the time of development, Please report this in the Cocos2d-html5 forum.