1. Constant lay offs. I worked there for 5 years. There was a massive lay off a year before I joined, a smaller layoff while I was working there, and another massive layoff a month after I left (dodged that bullet!!).
2. Not good for those seeking a Green Card sponsorship. Again in lieu of the layoffs. I don't know about the complaints against HR being unresponsive. They always seemed very prompt in their responses to me.
3. Not much chance to grow, uncompetitive salary. This was almost definitely because the company struggled to be profitable the whole time I was there.
4. Point 5. from the pros. Sadly, not all tech teams are top notch. If you land up on the Data Management Platform team or (possibly) certain parts of the AdServing team, life's good. DevOps was also getting right up there. Other teams were a little chaotic, bad engineering practices over the years coupled with "shiny object" syndrome.