I passed through this park on my way to the Ghibli museum, and have to say this park is one of the best in the world!! The park area is massive, with lots of greenery and a huge lake in the middle of it.
The whole place is full of sakura, and when in bloom that really makes for an incredible sight here! I was there just as the sakura were starting to fall, which meant a lot of the paths were covered in a thin layer of pink petals, which was really lovely to see. And as many of the sakura line the lake, a lot of the leaves also drop into the lake forming a pink petal wallpaper over the surface of the water, which again is a truly wonderful sight! This is now one of my favourite sakura spots in Japan! Even rivalling some of my top ones from Kyoto and Shiga!
Another plus is this park seems popular with people walking their shibas, and if you ask politely in Japanese they are often happy to stop to let you take a photo, and/or pet the shibas! :D
The park is really peaceful, but it is also only a few minutes walk from Kichijoji station and the shopping area around it. Though if you want a drink or snack then there are a couple of cafés in the park itself. There's also a zoo, but I'm not sure what that's like as I didn't go in.