It depends.  If I'm going downhill, I keep it in gear to engine-brake.  If I'm going down a steep hill, I gear down, tap the gas to rev-up and then engage the clutch to get more engine braking.  If I'm going uphill, I let it coast.  If I'm on a level surface, it depends on whether it's clear to coast in neutral, or if it's crowded then keep it in gear to be able to quickly accelerate again.  I guess it all comes down to "driving skill" !!!