Say what you will about valuations in general, but Snapchat is rare in that they've produced a physical product and set some sort of future goal in hardware (specifically cameras). So If everyone else gets a C, I'd at least give them a C+.
The last Uber I ever took was a 20 minute drive that cost me $3.75 — I had a conversation with my driver about his cut of the fare, and tipped him because I felt guilty about how absurd it had become.
Uber's recent losses are unparalleled and largely stem from driver subsidies because they aren't actually charging a sustainable fare for the service they contract.
I honestly don't think they're a real company. It's all a farce.