I may have a few ideas up my sleeve in the graphical department for requests...
My level-up system gets gradually slower and slower as you move on (and the enemies are supposed to get tougher as well when you progress in the game: what you're seeing right now is the weakest enemy of them all, and they will eventually attack, but it's quite weak), but it's relatively quick to start with to get the player in the game (and to give them some encouragement to whack away at the enemies, as the first boss, which I myself jumped the gun on the statistics, is intentionally quite easy), but that's because the amount of EXP required gets gradually bumped up each level. Level 10, which I haven't gotten to yet, is where the EXP starts taking off, and once you really get up there (I'll say around level 50), you'll eventually end up with more than 10,000 EXP. The EXP, in addition to level-ups, will be my little method of scoring.
Another little secret: There's no text drawing in the GUI. Even the numbers themselves aren't pure text. This is part of the intended optimization.
Right now I'm working on a little feature of mine: you can just jump right into the enemy and "kick" them. Doesn't do much damage (unlike our human feet, a furby's feet doesn't have much force behind it. Plus, it has bad range.), but it can take out an enemy with very low health.
Plus, there are going to be a few towns to visit as "intermission" stages (you will be earning "gold" from some defeated enemies, which can be used at shops...).
Some of the items you may be collecting are only good for throwing at enemies... if they really are like that, once I get the item system implemented, I'll let you know which ones are the ones to throw.
Update 8/18/11: It's bug reporting time by me! I just found an interesting little bug called "The amazing flying furby!". You need an enemy on top of you for this to work, and he needs to have stopped moving. Now, just keep pressing jump many times over and over. This is a case in which I should add something that prevents the player from hitting jump after a certain amount of time to prevent said bug from occurring (this same thing also prevents the player from kicking if he's trying to jump... eh, I'll leave that in as a way to tell the player you can't kick if you're being trampled. Use the sword instead.).