I like running hills. Several of my running routes send me to run up into the hills, and I'm treated with some great views.
Yes, the uphills take more work. I know training on hills engages my quads, and I love seeing new muscle definition! And I sometimes feel like a skier when I'm cruising downhill. When it's rainy, I occasionally worry about slipping and falling on slick descents. But the change of pace feels good and helps the time and miles pass by.
My next goal race is the SF half marathon on July 26, and it will be a hilly 13.1 miles. So I will continue to do workouts that include hills and will embrace the burn in my quads.