Stumbled on this item in the bazaar last week for 10k. I figured I might as well have an item to cure disease since I'm always having to switch spell slots around ( annoying ).
I figured I had overpaid, until to my surprise, I found it was usable by ALL CLASSES as well as being castable from inventory!
Sure, it's not as good as it used to be ( insta-cast vs 1 second ), but it's still an amazingly useful item. I hotkeyed it and keep it in my inventory slot, so when I, or a group mate, get slowed / diseased I spam click the shield, and in a matter of seconds, target is cured.
As others have mentioned, it works on most slows as well. It's just one of those rare items that can be extemely useful at times.
Saves a spell slot, saves mana, saves time, and most importantly, saves your *** =)