I applied through an employee referral. The process took 2 months. I interviewed at Meta (Kirkland, WA) in Aug 2015
Interview
Asked a friend to refer me. Was contacted by a recruiter within two days. Quickly scheduled a tech-screen (essentially mini-ninja interview). After that came the on-site loop.
2 ninja, 2 pirate and 1 jedi interviews. Can't share specific questions, but plenty of other people did already. Unlike Google (interviewed with them also), Facebook seems to have a smaller question pool as one of the system design questions I got I've also seen on Glassdoor before.
I recommend going through the information recruiters provide for interview preparation. Since Google and Facebook use very similar processes, "Stevey's Blog Rants: Get that job at Google" post is also quite relevant and useful. Know your data-structures, algorithms, practice solving problems for a few weeks and you should be in good shape.
For system design questions, you will be asked to design Facebook-scale systems. Think data way beyond the scope of one machine, billions of items, thousands of requests per second. Hands on experience with such systems is of course "the king". In the absence of that - study distributed NoSQL systems, MapReduce and similar things and you should be in good shape.
Overall I was very happy with the on-site interviews and the level of support Facebook recruiters and engineers provided me. This was probably the best interview experience that I've had.
Having a competing offer handy will surely help you negotiate better compensation. Facebook seems to have an awesome culture. Deciding to reject their very generous offer for another one wasn't an easy call. One really can't go wrong by joining Facebook.
Facebook is the only company that I know that provides interview feedback. Regardless whether you pass or not I recommend asking for it as it will help you get better.
Interview questions [1]
Question 1
Data-structures, sorting, Big-O notation, large system design.
I applied through an employee referral. I interviewed at Meta (Seattle, WA) in Oct 2014
Interview
straight-foward coding and design. 2 coding interview, 1 system design interview, and 1 hiring manager interview. recruiter is very helpful. it's a very nice experience. interviewer are helpful and kind. Everybody is very friendly.
I applied through a recruiter. The process took 5 days. I interviewed at Meta (London, England) in Feb 2015
Interview
Telephone Interview followed by on-site. Process was exceptionally well managed and very well thought through and very efficient. Interview presented an excellent impression of the company and the people who work there. Never had a process that completed so quickly and with so little friction. Highly recommended. Would happily interview again! :)