I wore one, though I never had before, and loved every minute of it! I felt elegant, and I figure that's the whole point of formal night
Despite having read lots of posts from people who are very aware of what others are wearing (and thus might be aware of whether they were dressed in a similar manner or not), I was completely oblivious; I would be very hard put to tell you whether there was another long dress to be seen on board or not. However, nothing made me feel out of place in the slightest, and I would do it again in a heartbeat. I bought mine for about $35 on eBay.
