So, while I have not been able to obtain a very stable FPS and chrome has crashed the page once or twice, there are a few things I have seen that have really impressed me.
-Voice-overs no longer have a delay. The moment the text shows up is the moment the voice-over begins.
-Dual-casting no longer results in one animation with two damages, every animation is a single attack. This is best seen with Ice Blitz or Barrage, as ice surrounds the opponent each time damage is done.
-Every patch of land looks less “grid-like” and a more natural part of the world.
-Movement (when my fps isn’t horrible) feels more immediate with each click.
-Overall improvement to the lighting has helped the game in a major way (especially noticeable in Draynor with the dark environment but bright windows shining through. Fantastic).
These are the things that really stood out to me in the HTML5 beta. Of course, there are problems, but those have been mentioned repeatedly and I’d hope they recognize the FPS issue. Try to keep criticism constructive.
(Note: I didn’t mention NIS Because there is a separate forum for that)