We did a homeschool coop for a bit when DD was a preschooler. Basically we met once a week and one parent would have some activities planned out. Some of the parents were laid back and the kids mostly played. Others tried really hard to teach the kids something or other, which IMO didn't go over as well. At least not with my kiddo. LOL.
DD is currently in a homeschool program, and there are some classes taught by parents and by teachers. So far it's all been very relaxed, exploring/experimenting stuff, which is really what works when there are all levels of kids in one group. Oh, there is a gym class that is more regimented, but that's fine and works for all levels as well.
I think a coop might be really great if it isn't too structured. I'd definitely try to get a better feel for what your neighbor has in mind before committing either way.
