Of course, there are always many causes and different factors at play - such as the economy, etc, that impact anything. But overall it has been mostly positive.
On the positive side, it has connected disparate networks of audiophiles that were scattered in cities over the world. It has created a used market that puts a value on gear and helps purchasers make better decisions. It has helped weed out bad dealers. It helps weed out bad equipment faster. It breaks out superior equipment ahead of the pack faster. It presents access to different opinions of audio experts, experienced hobbyists, and magazine writers much easier allowing better decision making for the consumer.
On the negative side, prices of new equipment have shot up to counteract the flourishing used audio market. (This usually manifests itself in class warfare types of posts and letters to editors,but the cause is the internet.)
Ultimately, audio is an experience. One needs to hear and experience the music. The internet will never replace that. No matter how Valin praises a piece of gear, a smart audiophile will always need to hear for himself before handing over the plastic card.
These are just off the top of my head... I will probably think of more.