Ron Amadeo has mixed feelings about the smartphone. He points out a lot of compromises. It is more expensive than the Nexus 5 ($649 unlocked versus $350 for the Nexus 5). It has a bigger screen, but Android Lollipop does not take advantage of that extra space at the moment. The camera is okay is daylight, but bad in low light. Battery life is worse than the Nexus 5. Performance is worse too:

In our experience, the Nexus 6 was slower than the Nexus 5. Apps took longer to launch, tasks took longer to switch, and sometimes—particularly during heavy multitasking — our Nexus 6 liked to get stuck and pause for a few minutes while it thought about things. It would often "chug" during our normal usage and in general felt like a slow device.

The only great things about this device seem to be The Ambient Display and always-on voice commands, which are stock Android Lollipop features. With Ambient Display, the screen switches to dim black-and-white mode when a new notification arrives or when you pick up the phone. Without the press of any button, you get a battery-friendly glance at your notifications. With always-on voice commands, you can use the Google Search app just by saying “OK Google”, no need to press any button again. The Nexus 6’s only merit is to be the first smartphone to have these features.