The hike is tough, but well worth it. A beautiful cascading waterfall around a small crystal-clear lake. Plus, you get 2 for 1 with the "spouting rock" just a little further up.
Yes, Spouting Rock is definitely worth visiting after seeing Hanging Lake. Although Hanging Lake is the main attraction, (and rightly so), Spouting Rock is unique too. How often do you get to see a waterfall coming out of a hole in the cliff? And the waterfall is such that if the weather is warm, and you want to, you can stand under it. In fact, it took me a long time to get a picture of the waterfall without people in it because so many people wanted to stand under it!