There are two different, very distinct play areas. The smaller one, right by 148th Ave, contains some water play activities. The much larger one, over by Old Redmond Road, has a really big, really fun climbing toy. (Well it is only fun if you don't have a child at just the wrong phase - good enough at climbing to get to the top, but not able or confident enough to get down! I've had to climb up many times!) For bigger kids this is really great. There are also other things around the really high climb for younger kids, plus swings and a sand box.
There are two parking lots, one near each play area. There are also two bathrooms - one near the small one plus another about halfway between the two.
Other perks of this big park are tennis courts, basketball courts, big open grass fields, and paved trails for practicing bikes and scooters.
Here's the park website, from the City of Redmond.