Pros
I was at NGINX for several years and finished around the time of the F5 merger. As an independent company, it was a fun and vibrant place to work. There were some growing pains in marketing, but overall quite positive.
Cons
Uncertainty, disagreement on goals, some stuff got advanced through skunkworks projects rather than the mainline plan. There was also a lot of engineering turnover at one point, but then things aligned and products were shipping reasonably well.