I was referred in by my friend, and they got back to me the same day with a project. They give you 5 days for the project, and it takes a lot of your time, so be prepared for that. If all goes well, within a few weeks you hear back for 2 30 min phone interviews. I did those but was unprepared for the depth of questions they asked. I was impressed by the professionalism of the interviews though, and they did a great job explaining Uber's culture. I was also impressed by their respect for the engineering organization - this matters to me as a previous engineer now turned product manager. Lastly, I could tell they were super smart. I would have loved to work with them but didn't move on to the onsite.