I can safely say that the team members working in DynamoDB are very skilled and they care deeply about the product. They really work hard and think of interesting solutions to a lot of problems that their biggest customers face which is great from a product standpoint. There are some pretty smart people working there.
Engineering, however, was a disaster story. Code is horribly written and very few tests are maintained to make sure deployments go without issues. There was too much emphasis on deployment and getting fixes/features out over making sure it won't break anything else. It was a common scenario to release a new feature and put duct tape all around it to make sure it "works". And way too many operational issues. There are a lot of ways to break DynamoDB :)
Overall, though, the product is very solid and it's one of the few database that you can say "just works" when it comes to scalability and reliability (as most AWS services are)
Engineering, however, was a disaster story. Code is horribly written and very few tests are maintained to make sure deployments go without issues. There was too much emphasis on deployment and getting fixes/features out over making sure it won't break anything else. It was a common scenario to release a new feature and put duct tape all around it to make sure it "works". And way too many operational issues. There are a lot of ways to break DynamoDB :)
Overall, though, the product is very solid and it's one of the few database that you can say "just works" when it comes to scalability and reliability (as most AWS services are)
I worked at DynamoDB for over 2 years.