This is quite simply put - magical. The stage and lighting is set up in the middle of a forest to cast a lively, romantic ambience. It actually gives me the impression of A Midsummer Night's Dream.
This is the perfect date spot or even for a group of friends. I definitely recommend this to those who love Shakespeare. Even if you aren't reading sonnets in your spare time, it showcases wonderful talent and creativity. I was impressed with a scene in Titus Andronicus which used interpretative dance to tell part of the story.
Admission is by donation which you can deposit in the boxes at the gates. Due to this it can get quite packed. I suggest coming 30 minutes before the show to find seats if you're not picky. Be prepared to come much earlier than that if you have a larger party or want to be seated closer to the front. It also tends to get much busier near the end of summer, so be weary of that.
You can bring your own food or buy snacks there. There are also picnic blankets or seats that you can rent for sitting on the grass.
Best of all, High Park is so beautiful you can enjoy it before or after the show. Be sure to venture out to the Botanical gardens and fountains as they are quite exquisite that time of year.