When it works, it's better than email. But that's only when it works.
It's really had to handle the mechanics of subscribing someone and you can forget about strong analytics because you don't control the subscription process. After a customer hits your ITunes subscribe link, you're done. There's little you can figure out in terms of whether or not they subscribed.
True, it's hard to track subscribers, etc. But like others have said, those subscribers are much more tuned in than say casual readers of your blog articles. Much higher level of trust with a podcast audience imo.
It's really had to handle the mechanics of subscribing someone and you can forget about strong analytics because you don't control the subscription process. After a customer hits your ITunes subscribe link, you're done. There's little you can figure out in terms of whether or not they subscribed.