Pro Supports custom root domains
To set up a custom domain, Amazon Route 53 has to be configured as the DNS provider with the domain registrar, two buckets have to be created and configured with the name the same as the domain - one including, one excluding www. A more in-depth explanation can be found here.
Pro Super cheap with a year's worth of free service
S3 storage costs $0.03 per GB and gets cheaper the more is stored, PUT, COPY, POST, or LIST requests are $0.005 per 1,000 requests and GET and all other requests are $0.004 per 10,000 requests. And with some restrictions is available for free for a year.