Here is my experience with Bluemix:
1. We needed to get bills to send to our accounting department. There is no way to get this out of Bluemix. We needed to contact 5 different people and send 2 different support tickets.
2. At one point we couldn't log into our accounts, the authentication server was down.
3. The docker container doesn't always get internet. Also it sure as hell is guaranteed to not have internet if you restart it.
4. If you use their SAAS databases, then some of them you can connect to from the outside world, but some you can't. And there is no way of knowing which.
5. Just because IBM makes a product available doesn't mean it works. We used NodeRED together with the IBM developed database connectors for DashDB. That connector will timeout after ~24 hours and then not throw any errors when you keep writing to it. Took 3 days to figure this out and fix it.
6. Their deploy system is nice, pity it brings down your service for 5-10 minutes even for deploys that are literally 100 lines of java code.
7. It's painfully slow to push images to their docker hub. Took 3 hours to upload an image with ubuntu and java. And our uplink is 50mbit.