I've used these robes alot on my Sorc, and they work for all level 0-3 spells (Metamagiced spells excluded), most notably it means you can cast a quickened fireball or a quickened haste if you're ever caught unwarded and need a sudden explosion or speed boost. They are very good, especially on lower levels. It is an Epic feat.
Also to note, most of the common wards you use are around lvls 1-3, so it is a timesaver when warding larger groups of people and you can save your haste for the actual battle.
I do think they should be made availible to wizards aswell, though.