I agree with most of what everybody has got down. We've done only Voyager cruises. The food has been fabulous, service exceptional, guest room spacious and luxurious, shore excursions fabulous/different/challenging.. but my husband and I would chg/add:
- no formal nights; we actually prefer Regent to any other line in most areas by far, but did select Oceania on our last cruise due to their no formal dress (and itinerary). We don't like packing that extra weight/space for 2 nights and frankly when on vacation, we don't want to wear formal wear
- continued restricted smoking. I know, I'm a non-smoker, but the reality is that most people are nowadays and to start allowing smoking in staterooms is just not going to happen. The days of having to smell stale smoke from previous guests or sharing a public room with smokers is hopefully over.
- better entertainment in the showroom; not meant to be a complaint, but we have had more entertaining entertainment on other lines, albeit it was a few years ago (so is this a trend?) Would like to see fun/great magicians, better comedians, maybe even some music that wasn't from Broadway - less pop..
- Our personal preference is no days at sea. I know many folks enjoy that break, but we'd prefer to have the choice of getting off and exploring or staying on board and relaxing. This is a big thing with us when selecting our cruises. First we select 3 lines to look at: Regent, Crystal, and Oceania (after our last one) and then look at where we want to go and what their itineraries are.
- public rooms on Oceania were nicer - larger, but still intimate; decor very appealing

That's our opinion for what it's worth. Age may be a factor I realize. My husband is 50 and I'm 48. We hopefully have a lot of years of cruising left and the more active we can be, in order to enjoy the gourmet food on board, the better.