Avantages
Amazon created and maintains a useful framework for quick decision making, self-development, and other useful career skills. Your first mini project when onboarding is basically to learn (or refresh) on these skills and grow yourself as an asset before you begin doing real engineering. This time alone is a long-term benefit to you, regardless of whether you succeed/stay at Amazon. You get immense autonomy and trust to decide your own path to success. Your managers set a vision for what success looks like in the future, amazon provides a loose framework for how work is done at amazon, and from there you create your own plan and manage your own time. It's liberating.
Inconvénients
Some folks *may* find the autonomy to actually be ambiguity, and may want more structure than amazon would like to give.