It's a bit tough to go through a hiring process through a staffing company; there are two parties (Fortitude and the company you're interviewing with) to manage and keep updated and keep in sync with everything. I get it, since they need to be involved the entire time to ensure everything goes by-the-book and that they get paid for the candidate placement. But it adds a little friction to the whole process and makes it take perhaps a bit longer than it otherwise would. Overall, for everything they provide (interviewing guidance, communication, background logistics, relationships with companies), it's well worth it.
Also, as I understand it, for most jobs you get through Fortitude, you will be on a 6-month contract working through Fortitude until the company decides to take you on full-time. This means you'll be on Fortitude health insurance, get paychecks from Fortitude, and have to deal with this extra set of logistics for the first 6 months, at which point you'll be transferred over to your actual company's payroll systems. But, again, if you get a job you like, not a big problem.