We just did this cruise in October. Miracle is great and very unique in it's décor! We loved it but have heard others call it "ostentatious" or "gaudy". Lots of fun areas to hang out in for whatever your mood is.
Dinner was pretty casual for the most part. Hubby wore nice jeans with polos most nights and dockers type slacks with a button down shirt on formal nights. I wore casual skirts with nice short sleeved tops on causal nights and semi casual cocktail type dresses on formal nights. There were people dressed more nicely and more informally than us each night. The captain, his wife, some of the officers and their families ate dinner in the MDR (late seating) at least half the nights and were all dressed very nicely each evening (evening dresses, full hair and makeup for the ladies, uniforms for the officers). Let me know if you have any specific questions and I can try to answer them!