As far as dining waits I've seen my time dining as the worst experience since they started out. They used to just have scheduled time (either 6:00 or 8:30) and no waits for anyone. However, people started coming in pretty late to the early seating so they decided to have anytime dining which doesn't mean you get the time you want. I've seen long lines for that on both the Summit and the Constellation all the way through the bar and into the foyer!
Having to ask for towels on Celebrity? That's just horrible based on how they used to be. I hope one of these days they start hiring more people and stop running the stateroom attendants ragged.
Just to add we've been on almost 80 Celebrity cruises over the years and also remember how excellent all the food was. Never had a bad meal back then.