I visited this park back in September of 2014 and I liked it very much. It is very true that it feels like a "secret" park, as it's kind of tucked out of the way. The only reason I know it exists at all is because of Lee, for whom it is a major part of his cycling route.
It is very pleasant to go for a walk and watch the water, or lie on the grass and look at the trees. There's plenty of wildlife to keep an eye out for in the river.