Its all about location but there isnt enough battery.
Most of the new software goodies that Google is bringing to android rely on one thing and that's constant location reporting. Unfortunately location reporting also happens to be an enormous battery drain, if I turn on Google now and location reporting then I can never last a full day on a nexus device. If I turn off location reporting then Google now becomes half as useful as it is supposed to be.
Now looking at the size of the nexus 5 battery, it is unfortunate that this is going to be the same story all over again. Either turn off some of the most useful Google services or be ready to charge your phone twice a day. Its really just ridiculous and very disappointing that Google doesn't understand how much of a battery hog their most useful services are.