You might want to check out some of the Amtrak discussion boards. I think you will find more feedback over there.
With that said, train travel is a journey. It is an experience. I think if you go into it with the that mind set it will help alot. It is going to be lot longer and more expensive that driving or flying. I would not plan anything for your arrival day. The train is going to be late. Sometimes can be many hours late.
Since you are traveling that MI, I believe you will be taking the new Floridian route. That is a long ride. It is two nights. If the budget allows I do a sleeper car. I wouldn't want to go coach that long.
Yeah if it’s the new “Floridian” route bundle, it’s a little circuitous. Plus from MI I think you’d need to drive to IN or OH to get on it (or take train towards Chicago then switch over).
I do love train travel, but for MI to FL it doesn’t seem nearly as quick or convenient or cheap as flying…