Pros
As an engineer: Expectations are very low. Little-to-no personal accountability. No one will ever ask you your opinion, or to exercise critical thinking, or to step out of your comfort zone. The development tools and infrastructure are so awfully slow that you have plenty of time to goof around, eat snacks, pick up a new hobby, all while waiting for your local environment to boot up. These points are of course actually all Con's if you have any aspirations beyond an easy paycheck.
Cons
KAYAK has long since ceased to be an innovative company. Make no mistake, this is not the scrappy, innovative, boundary-pushing KAYAK of 10+ years ago. If you've read the book "A Truck Full of Money" (about the company's founder and its early days), do not expect it to in any way resemble the company described in the book. Pretty much all of the company's original visionaries and A-players have long since left, and it is now a complete shadow of its former self. Today, KAYAK as an employer feels akin to a forever-busy, rich businessman dad who showers you with shiny gifts and money but never puts in the time or effort to actually be there for you. Tech industry perks like free snacks, massages, happy hours, and ping pong abound. But almost zero effort is put into helping employees build their skills, take on additional responsibility, or advance in their careers. The leadership fundamentally does not care about anyone, despite their continual statements to the contrary. This is probably because their revenue continues to climb year after year despite minimal improvements to the product, and numbers are all that really matter to them. Indeed, from a technical perspective it seems KAYAK has basically been in "maintenance mode" for many years now. The service they provide is fundamentally a solved problem now and has been largely commoditized with dozens of other near-identical competing sites fighting for a share of the pie. Engineering effort is primarily spent chasing and patching the absurd amount of bugs in its horrible code base rather than tackling new problems. What little experimentation that does happen mostly just boils down to tweaking the UI and moving things around on the page to increase conversion and ad clicks. Having no agenda for big technical endeavors, KAYAK has allowed its engineering organization to decay into a terrible state of dysfunction. Talented people are leaving constantly, taking most of their knowledge with them (because hardly anything is documented), and they are being gradually replaced by less skilled engineers. Consequently, mediocrity and status quo reigns here now above all else. New ideas, innovation, and creativity are not only NOT encouraged, but often actively suppressed. It seems just about every idea put forth is met with some form of "it just can't be done" / "that wouldn't work" / "that's not how we do it here" / "that's just the way it is". Sadly, most line managers really are genuinely nice people just trying to do their best, but basically have no license to do anything because of lack of support from upper management (most of whom don't understand software management). Communication and collaboration between teams is almost non-existent, and when it does happen it usually goes very poorly. The company mantra of "No Stupid Meetings" sounds great on paper, until you realize the result is that no one communicates with one another, managers have no idea what's going on and everyone is re-inventing the wheel every day because teams can't figure out how to collaborate or effectively share resources. Ask yourself, is this the kind of environment you want to work in? When you could instead easily go to any number of other tech firms where people still want to try, to learn and improve, to push boundaries and change the world? KAYAK is not that place anymore.