Ventajas
Amazon has a strong bias for innovation and out-of-the-box thinking, and tends to ignore title/position -- anyone can invent. They have a "Just Do It" award that is given to people every quarter for stepping outside of their job and creating an innovative solution to a problem, which exemplifies this bias. Amazon has a strong commitment to these innovative ideas, and doesn't have the "sink or swim in 9 months" mindset that many other companies have. Amazon sticks to an idea to see it through. Amazon offers a reasonably balanced work environment, and expects you to have a family and friends outside of work. You work hard, but you can also have a life outside of work.
Desventajas
If you're looking for just 40 hours a week, Amazon is the wrong place. Realistic hours for a technical position are 50+ per week. Q4 is a special time of year, so if you like taking the month of December off work, Amazon isn't somewhere you should look.