They lose the bonuses to Climb, Jump and move Silently, but gain bonuses to Appraise and Craft checks with stone or metal.
They also have Stonecunning and Darkvision
“These halflings are shorter and stockier than the more common lightfeet.
Deep Halflings are about 2.5 feet tall and weigh between 30 and 35 pounds. Deep halflings speak Dwarven fluently.