I have not used the 8 series yet, but have noticed the following observations from my colleagues that would explain the luke warm tepid response. The consensus is while the A11 processor is faster than the A10, it's hardly worth dumping your iPhone 7 series for. It is definitely worth moving from the 6s and older models. Interestingly, but not surprising to me, the iPhone 8+ is outselling the iPhone 8. As this model has a better super retina screen, better battery and the dual optical image stabilization that will be also found on the iPhone X, why not go big?
Apple told the public that their glass back, necessary for wireless charging, was extremely durable. That apparently was a lie since folks are already having them shatter after dropping them. Today, the iPhone 8+ is clearly the best Smartphone on the market. The biggest problem Apple has though the 8 series is already obsolete. It has the same old boring look of it's predecessors but more importantly, does not support T-=Mobile's new 600mHZ "Band 71" which is going to be a deal breaker for me. In fact, the iPhone X will not support this band either. As T-Mobile spent $8 billion to obtain this special bandwidth, I'm not spending big bucks for a device that does not support it.