There are a lot of neat trails here- I probably shouldn't recommend getting off the main trails but when you do you find little trails going everywhere. There is enough use that people have worn trails in a lot of these areas- down most of the canyons and up to the indian shelter overhangs along the cliffs at the west end past the old bridge. Most of the hiking is easy to medium. A little climbing can be found and in and around some of the canyons it could be dangerous for careless hikers or children. It's big enough that you can get lost- we came out in a subdivision on the north side once, but basically it is a contained bit of nature and there's no real fear of getting lost or anything. Check out the dam spillway at the extreme southwest of the park.
Rarely have we encountered a lot of people, but it is usually fairly active. We have never encountered any undesirable activities going on or any people there to do anything other than hiking. We hiked here to gear up for Guadalupe and I recommend Miller Springs whether you're just out for a walk or want a fairly good challenge.