It's a boys' club. They might be able to claim equal or near-equal numbers, but the underlying culture operates like a fraternity.
Managers and leadership make decisions on direction and key projects quickly and not based on data. Priorities shift constantly and the most important thing one day is not the most important thing the next. People spend a lot of time on things that ultimately get scrapped or aren't useful. There are tons of side projects that aren't counted as part of things like performance reviews, but still take a lot of time. There is a difference between adaptable when necessary versus having to be constantly adaptable.
A majority of the senior leadership team have been at Bullhorn for a long time, some not having their titled roles at other companies. This is a problem because they don't have any experience/training elsewhere, having grown into their roles at Bullhorn, and this occasionally manifests as not knowing their discipline well.
If your calendar isn't blocked solid for the day, requiring you to fit in actual work elsewhere, you're not working hard enough. Feeling like you did a good enough job even though you're working your tail off is almost impossible.
They talk a lot about company culture, but it's not organic or realized in true day-to-day work life.
If you have any depth in your field, there are plenty of other companies who will value that. Don't invest in landing at Bullhorn only to realize by 6 months that it wasn't what you thought it would be, and be looking for other opportunities (again) by 12 months.
Also my hunch is that they are writing a lot of the 5-star 'wouldn't change a thing' reviews, because they all sound the same (and simply can't be true!).