This card works fine in the Galaxy S2. I took a class 10 card to be sure of not having a performance problem by installing applications on this map. By cons as I have no other I have not been able to verify if it really brought something.
The adapter might be convenient, but in fact as it is hassle to remove the phone card, I prefer to connect the phone directly to the PC via USB to access the map, which is done without installing anything. So I'm never used.