I do all my genealogy there and it's great. I haven't seen any vandalism problems, but there are data quality problems and poorly sources facts (a link to ancestry.com is not a useful source!) that you have to deal with, but you can generally fix problems created by others, or at least leave comments explaining why you think it's wrong.

Oh, wow, that's exactly it! Thank you.

It is great, except it could use a UI/UX overhaul. I guess the barrier to entry keeps the data quality better but it could benefit a lot from simple quality of life updates.

Basic things like being able to attach sources to data points (like birthday) at time of creation.