I picked up a flyer for WikiTree at the Midwestern Roots Conference, so I thought I would give it a whirl. It was not a program I wanted to work with.
For one thing, I have a tree on Ancestry that I have devoted a lot of time to, along with adding a lot of resource documents, so I don't need another tree to maintain.
You have to be "recommended" to WikiTree, which irritated me right off. It's a free site and you will be doing the work, so what's with the filtering of membership? I found someone to sponsor me on the site--they didn't know me, so that seemed a little Mickey Mouse.
The security settings seemed overly complicated for my simple soul, and the data loading was also. I had to keep chopping down my Gedcom to make it small enough to load, so the limit might be a little low for long-time genealogists.
When I decided to cancel out, they dropped my membership, but kept the other folks I entered. Any free data is a boon, I suppose. Anyway, if it's your only online tree and you are willing to do the data entry, I guess it's an OK site. It's free, but time intensive. I'll stick with my Ancestry bit. Somehow I trust folks with a monetary incentive--comes from my Yankee background!