First of all, I like Left 4 Dead, despite the childish title. The game is fun, but there are a couple of things I want to complain about.
The Hunting Rifle is totally lame. Sure, it's the only gun that can reliably kill something from very far away, but you can only aim when you're safe, and you're only safe when you're not able to see very far. Its other ability, the power to penetrate through most objects, only sounds good until you understand what that actually entails. First of all, bullets can only go through brushes, which is a technical term for things like walls. Bullets can't go through cars*, trash bins, or boxes. Also, bullets can only go through one brush, so if that Hunter pinning your ally is behind two plywood walls, he may as well be on the moon.
L4D's newest addition, survival mode, is a good idea, but I'm not sure how I feel about it. It's inherently somewhat frustrating, but I think it's more frustrating than it has to be. I think I'd enjoy it more if it was less intense. There could be difficulty levels, and the easiest mode would let you play in a way that's fun without getting totally wrecked.
*Even the windshields and tires are completely impenetrable.