Good gameplay is not a property of the platform (e.g. HTML5 or Flash), but of the game itself. Since HTML5 is still very young, there are mostly web devs building games with it - which often results in games that "feel" wrong.

But I agree, this game is a very nice example of how to do it right.

Also try http://www.phoboslab.org/ztype/ or http://playbiolab.com/ :)