I have sailed on 6 RSVP cruises , the last one was in 2001.
Roommates: 1 was superb, 3 were OK, 1 was from hell and 1 trip I did as a solo.
As an avid cruiser...56 ships under my belt, traveling solo has been the norm for me on a straight cruise. I think that having a share roommmate is more fun on a RSVP cruise as long as the roommate is considerate and does not attempt to take over the cabin as if its their space in total. Yes it is a crap shoot, but I think it adds a little more excitement to the trip to hopefully make a new friend. Me, I ask only a few things up front.1 Put the do not disturb sign out if you are "entertaining". 2.Entertaining should not be after midnight unless already discussed and agreed to.3. Do not use my bed for "entertaining". 4.For safety sake, don't leave the cabin looking like a cyclone hit it, tripping over clothes left on the floor in the dark can be dangerous, especially if you have been drinking late into the evening.
If these requests are too extreme, then the sharing of the room with me could put a damper on my experience but not sour me towards my roomy except if my bed is used so as to keep his clean....that was the roommate from hell.
For me, I have booked a share for the Westerdam next Feb and am anxious to meet my roomy. I intend to have a great time and if I can add to my shares experience by being a good roommate, I will do everything I can do do that.
So give it a try and do a share....you might make a friend, you might never see him, you might 'Click"....you never know....just go have a great time and be considerate. If he turns out to be really bad, let me know........we can help "motivate" him to be nice :^)