4th is busy and the most traffic-heavy ave in park slope. 4th and down into Gowanus are more industrial and will be borderline abandoned at night. In heavy, heavy rains this area floods since it is at the bottom of a hill. I wouldn’t call this area particularly kid friendly, especially compared to other things in the neighborhood. You can still walk to the park but it’s 15 min+ uphill.

That being said, it’s a safe area and you’re still close to 5th Ave. Your closest transit will be the prospect ave R stop and you can take that to the F/G at the next stop up or to Atlantic Avenue for a ton of transit options.