Willis towers watson sucks on the casualty consulting side if you are an experienced credentialed actuary.
Probably ok if you are entry level looking to work in a fast pace environment with exposure to a variety of projects. Get your credentials and move on.
More generic advice about companies: if you can, it’s better to speak with both someone currently with the company and someone that left. Sometimes those no longer with the company may have an axe to grind. Maybe they were a low performer. Maybe they just had a crappy boss and others in the company may have a different experience.
Agree that those in the department you are interviewing with may sometimes have an incentive to paint a rosy picture if they really need help. If you have a connection in the company outside the department, give them a call.