I am using mywedding.com too. I am using it in conjunction w/my site for my TA.
I liked that I could have my own personal space and my TA wouldn't be able to see it. Plus I am totally using it as a pre travel RSVP because I honestly only want to put the people on my guest list on the TA site who are showing interest. I don't want to bombard people with wedding stuff when they aren't interested. Ya know?
It is not finished yet,but I love how I can keep updating it and posting it to facebook