I've walked by the spur trail, although I haven't been in the campsite itself. The views from the Belly River Valley are relaxing and always get me excited about what's to come.
No matter which route you do to get to Gable Creek you will see some magnificent scenery. The camp itself is in a protected pocket of forest but the Belly River is close by and Gable Creek is there as well. A short walk from the camp will provide a spectacular spot to watch the sunset. Also it is only a short hike across the Belly River to Gros-Ventre Falls. If you are not hiking up the Mokowanis Valley consider the evening walk to the falls.
Gable Creek campground is about 1/4 mile off the Belly River trail just before reaching the Belly River Ranger Station. The site is about seven miles from the Chief Mountain Customs Station. The site is largely wooded and near Gable Creek so one hears rushing water from the campground. The site is not spectatular but certainly adequate. Given the choice and without other considerations I would pick Cosley Lake over Gable Creek because of the scenery and location.
At the time we made a campsite reservation in 2005, Gable Creek was our only choice. It also served our purpose well in that it was a relatively easy backpack with plenty of opportunities to do additional hiking beyond the campsite.
If you stay at Gable Creek, hike in early, set up camp and then hike either to Cosley Lake and beyond or to Elizabeth Lake. Or check out the Bear Mountain trail.