The two biggest struggles I've had working here are with the hours and employee turnover.
It's a good thing the people at MaPS are fun to be around, because prepare for work to be your social life. The other reviews really don't exaggerate the situation: you will be working from 9am to 8pm Mon-Thurs, but more like 9-5 on Friday. People joke about feeling guilty "leaving early" at 7pm when they're projects aren't busy. Research analysts are staffed on 2-3 projects depending on staffing needs. Different projects have different reporting schedules, some are pretty constant month-to-month, others are crazy busy quarterly or bi-annually, but relatively slow the rest of the year. If you are on one of the quarterly or bi-annual reporting projects, be prepared to be working 60 hour weeks for about a month. If you have the fortune to be staffed on two projects like that, then you're really in for a treat. That being said, realize that MaPS is a heavily consulting-minded company, and those sorts of hours are accepted in the consulting industry. Just be very aware of what you might be getting into.
A related issue is the employee turnover. Burnout with these kind of hours is not all that surprising, and the company is actually set up to accommodate this, for better or for worse. They constantly are hiring new employees, but that is because they occasionally go through month-long periods of having one employe leave every week. Usually it's research analysts who have put in their "2 years" and then moved on, but occasionally it's project managers. Unfortunately that means your project teams constantly have to play catch up and onboard and train new team members. If a project manager leaves, you might be stuck for months on a project without a project manager. You get an opportunity to take on more responsibilities (and this will defiantly show up in your annual career review), which is great if your other projects aren't busy. Otherwise that starts to pile up fast...
The fact that this kind of turnover is expected and seen as acceptable kind of gives the place a sweatshop-like atmosphere. Honestly I think most of the employees are so young because they are the only ones who would be willing to put up with those kind of hours.
That's not to say that the hours aren't worth it. If you are serious about any sort of career in market research or consulting, you will get a LOT out of working here (and people who do stick around have no trouble finding some pretty impressive next jobs). Just be ready to commit a lot if you take this on.