The Kern River Valley is my parents' new home. I've never been all that impressed, finding it too hot, cold or windy most of the year to really enjoy any outdoor activities.
There is lots of camping available around the lake and up the northern Kern River. Beware the south Kern River, between the lake and Bakersfield, because it has claimed many lives due to strong undercurrents.
Kernville offers a cute little golf course, cute little park, cute little restaurants, and cute little shops and a museum. You can also take rafting tours. It's been my favorite destination in the area, and wealthy people are starting to take notice and build nice ranch homes and getaways.
Kernville is also a gateway to many Sequoia groves, including the Trail of 100 Giants, about 45 miles northwest of town. These trees are well worth a visit if you get the chance. Just head up highway 99 and then go west on highway 50. The trees range from 500-1500 years old, and the grove contains trees with a diameter as large as 20 feet and as tall as 220 feet.