I'm back from Westerdam with the promised report on the vegetarian menu. What they don't state in the press release (unless I somehow missed it) is that orders from the separate 22-item vegetarian menu need to be made the night before. This is no different from someone who has, say, a food allergy and needs to review the next evening's menu in advance. This is not a huge problem in and of itself. The problem is that with additional new vegetarian items on the main menu, there might be something that I'd prefer on that one, and I wouldn't know until the following day.
Easy solution, though: Simply ask for the next evening's menu while you are at dinner. If nothing appeals to you, request an item from the separate vegetarian menu. (The separate vegetarian menu remains unchanged throughout the cruise.)
As for the food, it's fabulous. Superb, really. Once I dig out the journal I kept during the cruise, I'll list some of the standouts. I do recall that the baked cheese polenta with mushrooms was wonderful, as was an Indonesian tofu dish I had during lunch one day. The cold soups were also terrific.