To summarise the whole process, I think Uber is one of the more tougher and lengthy ones out there. The first step is obviously to apply with a CV and they will then call you or email you prompting you to complete a 2 hour timed assessment. This assessment is done on Excel and you need to be comfortable with filtering out values and being familiar with basic business concepts. The second part of the assessment is more essay writing, I assume they want to know how you think. All in all, the assessment is tough if you're not using Excel every day.
The second stage for me was a phone interview asking me more about my past experiences and what I look for in a good workplace. This phone interview lasts about 20-30 minutes and is with someone who isn't technical so they won't dive into technical details.
The third stage is a video interview with the team manager and here you'll need to talk about your technical experiences in good detail. They'll also tell you about what the team does and it's more of a conversation if you're good at interviews, otherwise I can imagine this stage being pretty interrogation like.
I haven't gotten to the last stage yet but this whole process took over 3-4 weeks which is quite long in my opinion.