Ventajas
The work is interesting because the company’s service model is so specialized. Current CEO and backing investors/advisory board know what they are doing and they are generally well respected by employees. In the past there have been serious "leadership" problems. Notably around a narcissist evil bully clown CEO that got outed together with his inner circle in 2018. Probably they are now poisoning morale at another company. But that is over now.
Desventajas
benefits, mainly. It happens that good consultants with "some" experience (say, 1-2 years) are considered absolutely senior at other companies because they got very knowledgeable in a short time. Unfortunately then often they change for large pay rises (like, +1000-2000 gross). For experienced consultants I estimate benefits are probably 15-30% less than large consultancy companies. But the colleagues and work are much more interesting than at competitors because it is so specialized. So far, fair trade-off. Training and promotion opportunities are generally limited. You have to fight for it.