Was referred internally, and got the Excel test literally hours later on a Friday evening. I completed it on Sunday, and it took me about 1.5 hours. Wasn't too bad. Knowing pivot tables like others have suggested is key. I got an email on Tuesday inviting me to a happy hour the following Monday.
The Happy Hour was no different than ones I experienced as an undergrad. There were about 100 candidates, and maybe 25-30 Uber employees. Just try to have meaningful conversations with everyone, and you have to hand them each a "business card" that they will have ready for you. Ask questions about their job functions, and get to know some of the people.
After that, it was about a week before I was scheduled for a phone screen. Literally the phone screen consisted of the recruiter asking about my salary requirements, and if I was able to schedule an in-person interview that Friday, which I did.
I went for the Interview at their DC offices, which consisted of 2 groups of 2 people asking normal types of questions, and in between there was an exercise. The questions asked were a mix of your standard behavioral questions and some questions about the logistics of Uber's operations. The exercise was pretty difficult, to be honest, much more so than the other excel test.
A week later I got an email saying they would not be offering me the job.