It's out in Japan now. Chris Kohler at Wired's Game|Life Blog gave his impressions on it. In chronological order:

http://blog.wired.com/games/2006/12/...f_mana_it.html
http://blog.wired.com/games/2006/12/...f_mana_ha.html (Giant enemy crabs!?)

And the big, in-depth view:
http://blog.wired.com/games/2006/12/...f_mana_ex.html