Slalom prioritizes hiring from big consultancies, in particular Accenture and Deloitte. Two effects of this are that they frequently hire for that culture fit vs. competence; and there are a lot of fair-to-middling Big-X consultants that get managed out of those firms that land at Slalom. A lot of the work is staff augmentation, non-strategic. Getting people billable takes precedent over meaningful work. Senior leadership is overwhelmingly from Accenture/Deloitte/EY etc., so if you are not from one of those firms you will most likely cap out if you want a career vs. a job. Slalom preaches diversity and inclusion from a background perspective, but currently their diversity initiatives are "for Women." Most Slalom leaders expect you to buy into the Slalom Kool-Aid, so if you are looking for cool work but not a religious experience, your career path will be hindered. Over the last 24 months, it felt like priority had shifted away from being the best consulting firm in the world to a quest to expand internationally and hit $1B in revenue, and if things have to be sacrificed to get there, so be it.
Oh - and benefits are far below industry average. 7 holidays, and 2 weeks leave which is inclusive of sick, vacation, whatever you need it for. Recruiting will dazzle you with alternative models and funny math. It often feels like you are working for a cheap accountant (for example, new consultants often get recycled laptops that are years into their depreciation cycle).
In summary - if you are an ex-Big X consultant that doesn't want to travel, it's a great place. If you are from a niche tech firm, industry, etc., you will most likely find it very hard to advance beyond jr. leadership.