I've spoken with both Amazon delivery workers and Amazon warehouse workers. Small sample set, but the delivery workers seem reasonably satisfied, and the warehouse workers seem abused.

In both cases former employees were more willing to discuss working conditions than current ones.

I've also spoken to Whole Foods employees. Those who were working at the time of the Amazon acquisition universally despise the new management, and those hired since the acquisition are indifferent. But everyone's afraid to actually discuss this inside the store -- they believe they're being closely monitored.