We were on the Sky to Alaska and had a wonderful dining experience. We were traveling with other couples so we always had pleasant tablemates if we choose to eat together. In fact met a new couple who we have become great friends.
Our experience has been totally positive the food and service were generally quite good and although we only ate in the French restaurant one night - (would have been more) we loved the food and service in that restaurant as well. The only bad dining experience would be that we wanted a table close to the window one night and they did not accomdate us - (we were willing to wait). We seldom had any lines at all and the waiters were efficient and professional.
I could see if traveling alone that you might miss out opportunities to get to know other people - our favorite part of cruising but you could always hookup with someone and go to dinner again if the chemistry is right.