Exceptionally good, but with some flaws.
First of all, congratulations on making an exceedingly fun game! I found the combat enjoyable and very well put together considering this is a free internet game. Whilst I'm not entirely sent on the arrow keys/calculator pad controls, they work and they provide a good replication of an arcade-style set up (with the notable absence of a joystick, obviously). I thought the characters were interesting (go Meissa!) and well designed with a pleasingly varied moveset - being able to easily access the command list in-fight so easily was a Godsend.
Regrettably, there are a number of flaws that are all too noticeable:
1) I, and it seems a lot of other people, have had the game freeze on us whilst loading. Quite frustrating when one is 5 battles into a story mode, and definitely a bug to be looked into.
2) The loading times themselves; whilst I appreciate you giving us a breakout-style minigame to keep us occupied (and it worked for me!), the ideal solution would be to find a way to shorten loading times. Admittedly this is a difficult task given the quality of the graphics/engine, but it would be a big improvement and would make the game seem to run much more seamlessly.
3) Only being able to save things via Facebook/Mochi. Fair enough, I assume that part of the conditions for your adverts/sponsorship by Mochi are shoehorning in their login system, but it's nonetheless a shame that on one of the biggest game sites out there (with its own in-built achievement system), achievements and other features are only retained when using an outside service.
If the flaws sound like they outweight the positives, they don't. I really enjoyed this game! I only elaborate on the flaws in the hope that it can be improved and made even better.
In my opinion this game should be on a rating of at least 4.15, and without the flaws I've mentioned I bet it could reach upwards of 4.40, so hopefully with time this already most impressive title will attain the success it deserves!