Definitely worth the visit. Located in Parque de la Reserva. Many water fountains, good place to bring kids to the jumping water fountains, remember is open all year but Lima gets cold in the winter and even at night sometimes during the summer, bring a light coat when you go a night.
There are water shows at night on the main fountain, with image projections on the water. There is a fee to enter the park, as far as I remember was less than 10 soles per person. There are some street vendors regulated by the city hall right outside the park and eating there is very safe compared to other street vendors in Lima.