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.
Amazing open source reputation. Very easy to have a conversation about the product with the experience of the modern web. Marketing generates the majority of business giving reps a great chance at success. Great office location as well.
Cons
Aggressive clique like culture with management that cannot enable or develop reps. Friendships are the foundation for upward development and not performance or merit based. Those who are unsuccessful can go half a year without hitting quota before there is any evaluation is their process.