No hardware acceleration on the browser just yet and still scripted canvas so that is slower.

So until WebGL, even then, OpenGL ES will still be needed for most games/interactives/apps until we hit 2GHz and about 1GB of RAM or higher.

Then things like Flash also start to perform reasonably enough, same with html5 animation. If they were hardware rendered now then they would be reasonable but still wouldn't be compared to compiled, native apps on the device. Just like desktop now only the current mobile hardware is the desktop hardware of the late 90's.

WebSocket support, canvas, svg etc is awesome for games though.