The snarl on Jhudora's face is there for good reason. Take it as a warning. Jhudora starts off asking for items that are easy to find, and do not dip into your savings. But after awhile the her evilness will shine through. She will start to ask for items that are costly, and putting a whole in your saving. If you can afford the more costly items, then you will be rewarded handsomly.
Leveling
Everyone starts at level one. If you complete level one, you then move on to the next and so on....You are given a time limit to find each item. If you fail, you will start back over at level one. You can attempt a level every 12 hours.
Jhudora's Avatar
There is currently two known avatars for this game
Finish a Jhudora's Cloud quest on Jhudora Day. Feb 4th is the only day you can get this avatar.
Finish level 20 of Jhudora's Cloud quest, and recieve this avatar.
You are given about 14 minutes to complete each level.
Around level 23 she starts asking for unbuyables. (items that can't be found via Shop Wizard.)
You have to wait 12 hours before you can do a Illusen's Glade Quest.
Rewards
Unfortunately you are not rewarded on every level. Just a select few levels give you a reward. Seems the higher level you get, the better the reward is.