Unless you're visiting from out of town in the winter and you want to cross country ski or you're just looking to walk around, there's no real reason to check out this BLM tract of land.
However, for residents of Anchorage, it's a great place.
In summer it's a great place to mountain bike and makes a great after work place to exercise your dog.
In winter it's even better, especially when you're feeling shut in. Many of the trails are groomed for cross country skiing. But if you just want to walk around, there's plenty of trails to get lost in. Many people up here use the park to skijor which is cross country skiing with your dog leashed to your belt. There is also a dog mushers trail that rambles around the park.
Walking to the the end of the airstrip in the middle of the park and back under the moonlight is a surreal experience.
On the south side of the park is a small ski resort area known as Hilltop. I don't really ski, so I can't tell you that much about it.
I urge you to get one of the maps online or at the science center and explore different trails. I live very close by and have created different hikes based on how long they take me. My favorite 90 minute walk is Viewpoint to Rover's Run to Moose Track, back on Viewpoint to Coyote, to Moose Track.
A great loop hike in the upper section is Spencer Loop which gives you great views of Cook Inlet, the Chugach Mountains and Sleeping Lady.
Be careful on the northeast side that you don't wander onto military reservation land.
Anchorage owes its uniqueness as a city for blurring the line between urban and wilderness. Bears are spotted frequently in this park, and in the summer of 2008, 2 people were tragically mauled. I myself have seen 2 coyotes. Moose are ubiquitous. Even in the city, please practice wildlife safety.
Stay off the dog mushers' trail when snow is on the ground. Those sleds can move mighty fast.
If you have kids, Campbell Creek Science Center is open during the week and worth a stop by.