After over 10 cruises with family or friends or even by myself, I went on my first VTG singles cruise last year. The people were great! Everyone was friendly and ALL of the roommates got along well! (It wasn't until I came back that I noticed over half of my pictures were of the people I met!)
As far as I know the only issues had to do with wake-up times (some people want to sleep in on vacation). I suggest going to every mixer they host. Those private receptions with other VTGers made it so much more than a cruise!