I agree. I feel so let down by iOS 9. They made a huge hoo haa about it at WWDC. Promised huge performance and stability as well as better battery life. While I cannot comment on battery life just yet, judging by a lot of post, Apple has not lived up to the expectations set at WWDC. It's all just been one giant marketing ploy. Perhaps iOS 9 will be what was promised by 9.4.1, but by then iOS 10 will be around the corner.
It seems like either Apple simply cannot keep up, or simply don't care anymore since they making their gazillions anyway.
Personally I think Tim Cook should be fired, along with Jony Ive. I don't like what they have done to Apple.