Taking your dog without a leash is acceptable once inside the fenced section, however for the safety of the other people and their dogs, make sure there are no issues with aggression toward other dogs. You can still be liable if your dog injures someone or their dog. If they are prone to this type of behavior, you may want to stay away from this park, or at the least make sure they remain on a leash at all times.
Due to the high volume of dogs that go to this park, Rampart is almost entirely dirt. The dogs running and playing and digging make it an issue for grass to have any chance of growing in this area. This does hinder the view but the benefits of having a fenced dog park may far outweigh that.
The fence itself is chain linked and roughly four feet in height. This means some dogs will not have an issue leaping over it if they want to get out. High energy dogs that are prone to run away may not be the best to take if you believe they will attempt and can make it over that fence.
The grounds are pretty well maintained and dogs that like to try and dig under the fence will have their holes filled prior to them making any real progress.
Overall this is a fantastic leash-less park. If your dog is not prone to running off, Palmer Park in the spring may be the prettier option, but the fence here makes it a pretty good place to take some less behaved canines, and a great place for dogs to make some friends.