Yew longbows require level 40 Ranged to use. They hit fairly hard, but are noticeably slower than shortbows.
They are predominantly used for money making. Casting high alchemy on a Yew longbow gives 768gp. On average, a Yew longbow costs 600gp, giving a nice 168gp profit per longbow (without subtracting the cost of Nature runes). You receive 75 fletching experience for stringing this.