Last month we migrated on of our parent company products from bare metal to Amazon cloud. This represents a huge step in uptime and failover capability in the short term and the ability to take advantage of cloud features such as Lambdas, microservices, fast readonly RDS instances, balancers, etc in the long run.
This effort was significant as gigantic amounts of data had to be moved both in database format and file storage format, lots of configurations had to be reviewed and changed, VPN tunnels had to be created in order to increase security, in summary, it was a significant effort that involved the whole team.
The best? It worked, worked well, and Amazon has ben a great partner as we already have other products and services with them.