Having just completed our second cruise on Minerva we think that its still doing things right. We shopped around the cruise lines at one time, and have sailed with some that we find too opulent, some with excessively expensive alcohol prices, some are too crowded, and some where the on-shore trips are just too expensive. Minerva prices are all inclusive, so do the maths and you'll see that the up-front price isn't always the cheapest in the long run.
The ship itself is comfortable, well staffed and the space per passenger is sufficient never to feel too crowded. its principle plus factor though is the supremely high quality and relevance of its in-board guest speakers who without exception combine erudition with entertainment, and who mix freely with the passengers.
Does it have a downside? Well, its quite small by modern standards and because of its loyal following, some "Swans" as repeat customers are called, are getting on a bit so don't expect a wild rock-n-roll atmosphere. They all have a 'can do" attitude though, and after dinner conversation is always interesting and sociable. Give it a go, but don't take the kids!