The very fact that they are dogfooding DynamoDB (with core features of their business) makes me want to take it more seriously and use it more.
I also love that they didn't just replace Oracle with <insert competing RDBMS here> but instead thoughtfully pieced together a strategy based on what the data was going to be used for.
Have used DynamoDB a couple times, most recently for data processing.
It is extremely expensive, for data storage and performance. Queries are limited and cumbersome to write.
If you are looking at it, put a reasonable amount of test data in and play with it too see what costs look like compared to the performance you need from it.
I have the exact opposite experience. These are just anecdotal experiences. Without providing insight into the workload and your approach it is pretty meaningless.
I also love that they didn't just replace Oracle with <insert competing RDBMS here> but instead thoughtfully pieced together a strategy based on what the data was going to be used for.
Well done!