Compared to PaaS provides, Amazon is easy to migrate off of because they are simply giving you virtual hardware. The basics of their setup are well known: Xen

Compared to PaaS provides, Amazon is easy to migrate off of because they are simply giving you virtual hardware. The basics of their setup are well known: Xen and Linux. EBS is some sort of block-based network storage. True, we do not know the backend storage setup, but it does not really matter. The Xen VM simply sees a disk device. NetApp, EMC, Dell, HP and many others all have products that offer similar functionality, including snapshots. The only part that is potentially hard to migrate off is the security groups, and then only if you are using named groups. If you are just using IP based rules, most any firewall would work.