I LOVE leather sofas and furniture. The one nice thing is that anything spilled on them can be wiped off and they don't attract pet hair and whatnot. They are pretty difficult to punture but not impossible (especially if you have pets) but then again, same with cloth. If temperature is an issue, a covering looks nice and adds to the sofa and the room.
I am not worried about pet hair so much as the cat's claws tearing them up.