I have one of these - I don't use it much though.
My husband brought me it back from France the last time he went. He's Algerian/French and this is what he is used to using for cultivating the ground. I thought it might get him to come up to the allotment and help me out, but no such luck!
Theres an Italian gentleman that I talk to at my allotment site and he uses one and also a two pronged version. I got him to show me what he would do with it and he used it for hoeing in-between rows. He also said he used it for digging out shallow trenches as well.
I have to agree with John though, I think its whatever you are used to because I still use my hoe instead of the azada, but I know whenever my husband wants to dig a hole or anything he just heads straight for the nearest pick axe or azada instead, he can't understand why we use spades at all!