This is, indeed, an A-OK little park, located just a stone's throw from the Montlake Bridge. It edges right up to Portage Bay at the eastern edge of Lake Union. It's about the size of a football field and pretty level, which makes it a good place for flat, grassy pastimes like playing fetch with a dog, throwing a frisbee, lawn bowling, whatever.* There very often seem to be small herds of kids playing here under adult supervision.
There is street parking nearby, though somewhat limited because this is a one-way residential street. Much of the view from the park is actually obstructed by the Seattle Yacht Club, which I suppose is fine if you want to watch Thurston and Lovey go get into their boat with Gilligan and Skipper...for the rest of us, there is still an ample amount of shoreline that looks out onto the lake, and some that even wraps around to the Montlake Cut.
Facilities are limited...a bench or two and some garbage/recycling cans, but no shelters or bathrooms. It's basically yer no-frills little park that has a nice view and gets plenty of afternoon and evening sun during the summer. It's small, but rarely crowded...a good place to eat a picnic and watch kayaks, float planes, etc.
*If you are a goose, this is definitely a good park for the goose-y pastime of eating grass and then going to the bathroom (#2). For the rest of us: watch where you sit. read more