The interview process was challenging but fair. Just about every candidate needs to give a presentation as part of the interview process. This was, of course, a little intimidating, but everyone was friendly and reasonable, with no "trick" questions. Forrester does this because so many roles here involve frequent presentations.
The process started with a phone interview with Forrester's contract recruiter. Then there was a phone screen with the hiring manager. I was asked to do some research "homework" to analyze part of their website, which took a while, but could be done on my own time.
Finally, there was a fairly exhausting, all-day on-site interview process, consisting of 5 or 6 one-on-one interviews, and a presentation which talked a bit about my history, as well as describing a project I did at another company while in a similar role. It was a long day, but I'd much rather get it all done at once that have to come back for a "round two" (which is always hard to arrange when discreetly trying to leave another company.