We are very curious and interested as well. We've talked to some couples who have been on the various lifestyle cruises and have some friends going on one next month (should get some more detailed info once they return).
All have said it was a positive experience. At RM last week we met a couple who had been and they were the only ones to have a non positive comment and that was they felt there was too much pressure. At first I was a little surprised by the word pressure, but basically they said that because of the sheer number of people on the ship you might meet someone then not see them again, leading to pressure to "act now". I get that but I also see that as a "nature of the beast" thing that you just have to account for. It could be a good or bad thing depending on your particular deal, but seems like you just have to be more proactive in general, strike while the iron is hot so to speak, if you want to see them again, state it, make some plans etc... or just accept that you might not see them again and move on.