Stage 6
Overall, a very good game, awesome visual style, gameplay is simple and fun, not much to complain about.
However, I haven't even got past stage 6. Some people say that the boss is really hard, I think he's just downright cheap and it requires more luck then skill to beat him. I got the pattern, block the spin attack, dodge or get hit by the first sword strike, then run in for an attack, he kneels and you use your downward slash on him. even following this tactic to the letter saw me still getting pushed back into the spikes by the monsters spinning attack before I could kill the monster. And after about five tries and still getting my ass kicked, I couldn't even complete MY combo, I would attack inbetween its 1st and 2nd swing, and before I could finish my 3-hit combo it would start its spinning attack again and interrupt me. However, I think that was a glitch so I think I can forgive it. Anyhoo, I'm gonna give it another try, but seriously, that guy is a real big piss off.
tl:dr - the stage 6 boss is cheap, not challenging, and for that you lose points.