I haven't picked up this game yet, but I plan to soon.
For those having trouble with the brush, here's an interesting bit of info I picked up from rpgamer.com:
"...the game treats its shapes like kanji, meaning there is a specific order that it will always recognize, no matter how badly you draw it. I don't know what it was supposed to be, but in general, I found that with circle shapes, going counterclockwise had a MUCH higher success rate than going clockwise. Anyway, if you're having trouble getting a brush technique to work, try drawing it in a different order."