It can be a very political environment, you need to have relationships with the right people to succeed in the long term. Often management is not concerned with how things are done, just that they get done. This trickles down the chain and employees are often viewed as resources to achieve a goal regardless of the impact to them. In many groups you either sink or swim and if you sink you can get thrown under the bus and can become the scape goat for a unsuccessful project or initiative.
I also agree with a previous reviewer that noted that TripAdvisor is keenly aware of glassdoor reviews and strongly encourages current successful employees (those that just got promoted, had a good experience, etc) to write positive reviews on working at Trip. While there may be nothing technically wrong with this, the approach seems odd for a company based on unbiased reviews.