it really is nice.. there is a brand new play structure thats great for little kids too. the best part is Bronte Creek, though. it's great for wading and catching crayfish, etc. my boys LOVE it there.
http://cms.burlington.ca/Page428.aspx
normally there is no fee to go, but if you reserve a picinic area for a family BBQ, i think there is a fee (see link below). you can always take a chance that the picinic tables will be available, but on the weekend it gets very busy.
http://cms.burlington.ca/AssetFactory.aspx?did=4796
hope this helps!