I used this forum a couple of years ago, when I took a cruise to Alaska on Crystal -- since this would be my first cruise ever, before sailing I wanted to find out what others felt about Crystal. When I took the cruise, I wasn't disappointed. As advertised, Crystal proved to be an excellent cruise line.
This year I just returned from a cruise on the mv Discovery, operated by Voyages of Discovery in the UK. http://www.voyagesofdiscovery.co.uk. I went with this line because they offered a three-day stay in St. Petersburg, Russia, versus two with other cruise lines. Since I was particularly interested in a comprehensive visit to the Hermitage museum, I decided this was a good choice.
I had read reviews of the Discovery, in this forum, which gave it mixed reviews, but decided to go through with the trip anyway because it seemed to meet my needs pretty well. Here are my impressions after the trip.