Similar experience with Dynamo here: it's very easy to get into a situation where it's unusable (rejecting requests) unless you pre-provision enough capacity. The act of scaling up capacity often takes 5-20 minutes, and then there are the limits on how often you can scale. The backup/restore options are very poor. There's no good way to clear a table besides deleting and recreating it, which can be a problem when there are stream listeners. The tooling around Dynamo, both first party and third party, is also pretty shabby.

Maybe I'm just using it wrong. I wish Dynamo came close to its apparent potential.