Version 4.0 has a completely redesigned UI and many functions aren't where they used to be. In fact, some are so well tucked away that they seem hidden, and more than one App Store reviewer believes certain functions are just gone.
For example, some customers are saying that scheduled adjustments are gone, but they're just harder to find. You must click on the thermostat first to maximize it, then a menu icon at the upper right will reveal things like energy history and the scheduler. When the thermostat is not maximized, the same icon does something else. Oops.
Nest Mobile app
It's surprising that tooltips or a help section aren't available. Even an email introducing the update to customers would have been a good idea.
Nest is a great company, and its thermostat has saved me a lot of money in the 18 months that I've had it. This latest version of the iOS app could have been a lot more intuitive. Perhaps we will see a quick update.
At any rate, check the slideshow to see the features many people assumed have been removed. They are there. Just poke around a bit.
Note to Nest: "Help" information is good to include when you radically change software. What appears obvious to Nest employees who live with a product every day, may not be obvious to consumers.