Quick & simple platformer with creative mechanics! Finished it a while back but decided to just drop a quick review while browsing through games I haven't 100%'d yet.
My only real issues with the game is the 1000 foes achievement and the general balance of the items/abilities. Stats are tracked except for "number of foes killed", and you need 1000 to get the medal.
For items, I find the most effective setups are based around the Mana Staff - which gives you the ability to regain MP by landing enough hits at the cost of greatly reduced atk. You can get around this drawback by having Ninja Hood + Viking Armor for maximum physical damage while still retaining the ability to cast spells, and then compensate by buffing yourself with the Temper spell.
For abilities, the most useful ones are Heal, Temper & Seiken in roughly that order. Heal is obvious, Temper boosts damage as explained above, and Seiken is the strongest spell damage-wise; ice fire & bolt are simply not worth leveling.
Nevertheless, it is one of the better games around here.