Wow, you must have had some fantastic cruises, we disembarked Iona on Saturday, same cruise?
We hardly queued at all, never for the theatre in 7 or 8 visits, nothing significant for the restaurants, always got a seat whichever venue we went too and I remarked how easy the lifts were to access. I thought the ship seemed really spacious.
Not sure why you would expect a different menu in the main restaurants and buffet, haven't they always been the same? In addition you can have a different menu in the Olive Grove, The Quays or the Chef's Table with no charge. There are also at least 4 others to choose from, with a charge.
Perhaps we were lucky or you are unlucky but that is a remarkably different experience.