I have the same question / concern.
I think it's great that AWS are offering their own flavour of Linux, but doesn't that result in added risk of vendor lock-in?
Whereas with an Ubuntu instance, one can change cloud providers quite easily [0], without being tied into AWS-specific Linux configurations [1].
[0] I think AWS is great, so this is more a hypothetical scenario.
[1] I say this knowing little about AWS Linux and the degree to which it has custom configurations that can't easily plug-and-play on other distros.
Would appreciate insight from someone who can speak to this risk from experience.
Ideally you build your software such that the OS is just an implementation detail that’s abstracted away. In the server world a switch from RHEL to Ubuntu is not as hard as a move from, for instance, Google BigTable to AWS DynamoDB
AM2 is able to run in other places so there doesn't seem to be much vendor lock-in compared to a service like DynamoDB, though.