Pros
Adyen is growing much faster than the market, has a very interesting development/sales-driven culture, and very happy customers. Relatively relaxed, but goal driven, flat organizational culture. Good, solid, smart, but not always "on-trend" technical and commercial choices. Multiple interesting office locations around the world. Talented, competent and nice colleagues without too much dead-weight. Lots of internal opportunities for professional growth, available to anyone who is prepared to reach for it. For an agile company, nearly everyone has a sustainable work/life balance - probably the Dutch influence. I like the company's stated values, which seem shared by most people who work there.
Cons
The Amsterdam office is more techie than some of the other sites, and there isn't much after-work socialization, as new starter it's not as social as other international businesses. (Overseas offices seem to have more fun together) The business is growing fast and everyone gets hit by the growth pains at some point - either organizationally or trying to get priorities set. Effectiveness and avoidance of technical debt is valued more than current fashion, so introducing new tech requires dedication and a good story, not just "I want to play with this and bring it into production".