The interview process and what to expect is described in great details over their website -- and they stick to it. No surprises there.
The process is very long ( even longer in my case, but mostly because of poor timing & bad luck : key people were on vacation or had critical situations to deal with ), but the recruiter who was assigned to me has been extremely professional, transparent and responsive through all the process : I only have good word for her.
They will give you thorough heads-up over every next steps, plus a quick debrief after. You usually know well in advance who you're going to meet (linkedin profiles are provided so you don't have to stalk them yourself ^^), with an agenda of what the interviewer will be focusing on.
There's been a few minor hiccups, but I believe this is specific to my situation; plus it starts with good intentions : after we went through the initial process, my hiring manager had a better grasp on my profile and figured there would be a better fit elsewhere in the company. We did a "redux" interview process -- that one went less smoothly, mostly because it had to be rushed to not over-extend the "main" process, and some infos/context was missing for the interviewers.
Once everyone had time to sync and discuss, I got to the last step, references, and then got presented with an offer. They requested contacts for 2 managers and 2 colleagues from the past 5 years, but only the managers got contacted.
Side note : Depending on the role you're applying for, you may have to pass a technical test. In my case no technical test was deemed necessary, however since most of my work was under NDA at the time of interview, I wasn't able to properly do the "portfolio review" (which replace the technical test for less technical roles) step. They have been very flexible an we managed to find an alternative approach (a design test) which has then been used as a basis to the portfolio review.