I have hiked approximately 110 miles in this area and camped at numerous lakes in the area for 10 nights. The trail is great, unless you run into motocycles. They are apparently allowed all the way to Frog Lake. I have nothing against these riders but their activity is loud and tears up the trail considerably.
The fishing is great at most of the lakes. I highly recommend Castle Lake and Walker Lake. If you are up for a challenge, go swimming in Lonesome Lake. The last time I was there was in late July and there was still ice on it.
The scenery is beautiful and there are plenty of camping sites all along the lakes. There are typically lots of horses and outfitters that frequent the area. They are all friendly and great to interact with if you choose.
Enjoy. This is one of my favorite areas in Idaho.