I agree its asks lot more effort.
If it is only three items, yes perhaps avoid coding the circle menu.

The idea of slots is heavy used in top notch iphone games also like Dungeon Hunter and others. good idea also.
Another idea is to assign items inventory to keys, like in Twilight Princess you can have the keys displayed on right upper corner with the item on top of key letter !




The most important is to make slots, keys or potions picture really attractive :
For exampel in Super Mario Galaxy all HUD indication are very attractive to watch , a real pleasure caus of very good design :



Well it's not the main important feature , but polishing it , will bring up the game , caus you see HUD all along the game.