Del Mar Dog Park does not have great shade, leaving you and your canine exposed to the sun on hot days. Plenty of water is available, but bring some sunscreen on a nice day. There have also been some reports of ticks at this park, so make sure you check yourself and your canine for ticks before leaving or use some active repellant. This park is located right off of Iron Horse Trail.
A large number of the complaints regarding this park come from the electrical wiring and transformers boxes located in this area. The constant buzzing seems to worry some or at least detract from the experience. Although this has been the source of most of the complaints, there seems to be no real concern for safety. Just for the perception of safety and the slight annoyance of the noise overhead.
There is an area with a bench seat and overhead cover that would appear to be a nice place to relax. The ground is covered in woodchips, which adds to the cleanliness of the park, but some visitors might find the lack of vegetation an annoyance, and the wood chips break down, get everywhere, and are easily picked up by your canine's coat.
Overall, this seems like a pretty decent park, and if you are in the area, seems like a good place to spend an afternoon. The park around the corner adjacent to the middle school seems like another good place to let your canine run, but that is not a leash-less park.