I love Queens Park! I take my pooch here now that he has cancer and can't play with other dogs. Technically it's not a dog park, but no one (including city employees) bug you assuming your dog is not harassing people or causing issues. Also, ALWAYS make sure you pick after your pet, other wise, you'll ruin it for the rest of us.
The city has been kind of neglecting the grass, and part of the park in under construction. Watch out for cyclists, as they use the park as a cut through to get up to Bloor.
I've heard that at night the park becomes a bit sketchy, but there is a lot of light and you're surrounded by major roads.
QP is a great place for a Saturday walk, coffee break or cloud watching.