I applied through their website and was contacted by one of their recruiters. The standard questions (found in other reviews but also a couple specific to my field) were quickly asked. It sounded like they had more questions, but since I answered them easily, they organized the next phone interview.

I had 2-3 phone interviews. They were all of medium difficulty, nothing super hard, but did require a bit of thinking.

I then did an on-site interview, which included a nice, small tour of the office, followed by four 45-minute interview sessions. They all started by asking me about my experience, a bunch of questions specific to my area, and then moved into whiteboard exercises. The whiteboard exercises were of medium to hard difficulty; some were relatively straightforward, while others required more thought. I had been practicing with a lot of online questions (EliteCoder, etc.) and had also completed a couple of other interviews that asked very similar questions, so that helped a lot.

Everyone was super nice and friendly.

I was talking about how Yelp wasn't that big in another country.

I then got asked, "Why do you think it isn't big and what would you do to improve adoption?"

That threw me for a bit during a software engineering interview.