We love the "pick your own time" especially when you have excursions and just want to relax and not hurry for a certain dinner time. We did not make reservations ahead as Cruise Fanatic has suggested as we never knew when we would feel like it. There were times when we had to maybe wait a few minutes but they give you a beeper (which is nice compared to waiting in line at the early or late dinner times) and you could go find a place to have a drink or whatever. What we did not realize the first time we did a cruise this way was that we could CHOOSE to either eat with others or not. All you have to do is let them know. Sometimes we like to enjoy others company and other times we just like to relax by ourselves and not feel you have to share conversation with others. The other good thing is that you do not have to eat with the same people each night unless of course you meet people you would like to hook up with again.
Hope this helps, we choose to pick our own time whenever we cruise now and it is available as not all ships have it yet but I had heard they were going to upgrade them all to have this option.