I've known several Amazon employees over the years, both developers (going way back) and warehouse workers (more recently). The developers have consistently described it as extremely taxing, but worth the pay. The warehouse workers described it as extremely taxing, but better than going hungry.

The funny thing about Amazon is they don't just profit from shill reviews, but they also encourage shilling by their employees to boost their reputation. For that reason, I strongly weight first-hand accounts by people I know over everything else I've read online.