If you want to be a consultant to have 1) a large salary & year end bonus, 2) an active & useful alumni network, 3) prestige / benefits / name recognition, then Mars is probably going to disappoint you relative to opportunities at the Big 3 Management Consultancies, or even consulting with one of the large accounting firms. That's not to say that compensation is bad, but all-in will probably come in at the low end of market rate. I suspect that this is a function of being a small firm that can't always push back on client demands - thus Mars offers great services at lower cost. The thing that gives is employee comp & work/life balance. In my mind, the quality & nature of the work outweigh some of these drawbacks, but not all.
Because it's a small company that is solely owned by a man who is no longer heavily involved in the day-to-day business, there is a deep sclerosis within the organization that retards business growth, internal visibility on your performance as a consultant, and any true effort at modernization. This manifests itself in a few key ways:
There doesn't appear to be any real investment in HR capabilities that grow the consultant pool, encourage retention, or improve the quality of the existing pool through effective training. I saw this a more of a nuisance than a dealbreaker, but many people who come in without having had prior business experience will find this incredibly frustrating because they are expected to do a lot without any real mentorship or intelligible knowledge transfer system. Training is basically "sink or swim", and the current crop of project managers are not good mentors. Project management is very poor, with timelines that are not well managed due to lack of attention/direction from senior leaders until the very end. Typically, if you are not comfortable forcefully managing up in this organization, your work-life balance will suffer. Unsurprisingly, turnover is quite high (20-25%+ annually, and definitely higher than that in the 6 months I was there).
Documentation on projects that could come in handy on subsequent engagements is very poorly managed, there are no centralized, automated, searchable resources for new employees. As a result, every project requires a degree of time consuming wheel reinvention. Valuable subject matter expertise is lost for no reason, and many of the mid-level consultants have large basic knowledge gaps as a result of not having been exposed to a particular business concept through their project work.
Mars presents an antiquated face to the outside world because it has made no investment in its website, in the format of its presentation decks (which I'm pretty sure are 20 year old knock-offs of old BCG templates), or in training on presentation skills to its consultants.
While you will receive feedback on your performance at the end of each project, there is little to no communication about how that translates into your career path, your year end compensation, etc. It appears relatively easy to move up through the organization from entry-level up to Senior Consultant within <5-6 years. After that mobility is severely limited as there is very little VP turnover.
If you live in Manhattan, your commute on the Metro North will be a constant source of frustration.
While Mars does not have an overtly sexist/frat-like culture, the firm does a terrible job at making female consultants feel welcome - it is not a place I would recommend to any of my female friends. There was literally 1 female consultant in Greenwich during most of my time there. This is partly due to the original pool of candidates (skewing STEM backgrounds) from which the firm draws its talent, but also the lack any female role models within the organization (all VPs are men). I don't see how management can remedy this easily, as the situation is largely self-reinforcing.