Dos Escuelas is a big square of a dog park with a nice big patch of grass. While the space is big, there is no separation between big and small dogs--they share the same space. That's not really a problem, but some smaller dogs can get nervous around bigger dogs towering over them.
That said, I've been a few times and the people I've met in the morning and evening are nice and welcoming and they seem to have mellow dogs. I've yet to meet an aggressive dog there. Also, if you like taking your pooch to the park at night, the space seems very safe--it's well lit and there are lots of people around even up to 10 p.m.