I think it's a really cool magic item, and one I'd love to have, though my DM told me it would be unwise, given that he was going to start the campaign by putting us through a mordenkainen's disjunction. Not cool.
"Let's see... you rolled a 1 for the potion of Cure Light Wounds, the scroll of mage armour and that small shield +1 you looted from the orc tribe..."
-"Bad luck !"
Anyone interested in a discussion if saving rolls fail for a 1?