Pros: Cheap, abundant, durable, biodegradable
Cons: Break slightly more often than plastic tees
By not using them on par-threes (I pick up an already-broken tee from the ground), I seldom break these, which effectively makes them last as long as any other tee. Not only do they rarely break, but unlike plastic tees they also don't bend, which means that even when the ground has frozen in the autumn, you can still get the tee in the ground.
Though their slim design makes them slightly easier to lose than, say, a Brush Tee, you get so many of these tees in a bag that simply does not matter.