Beautiful park - especially on a hot day. They trees are amazing and provided a much needed shade for a respite on a sunny day. The park is not too large but it is well organized not too crowded on a Saturday morning. This is also where you will find the famous Meiji Jingu Shrine.
There were groups of Japanese students learning English that were stopping tourists to practice. We met a couple of ladies and had a nice chat with them.
One tip: some of the alleys are covered in small stones and it could get pretty dusty when ppl are walking by and irritate your eyes and throat.