Pro Up to date with the latest Android OS
As a Nexus, it will always be near the front of the line when it comes to updates. You can expect the latest updates weeks or even months before other more expensive phones.
Android 6.0 adds some really great features such as Doze mode, which puts your phone into hibernate mode when it's not in use. As a result, the phone will hardly use any battery at all when dozing. The phone will still periodically check for updates when dozing.
6.0 also introduces a native file manager, memory manager, and granular app permissions.
Pro Decent speaker
The speaker faces forwards which helps direct the audio towards you, meaning you never need to cup your hand or worry about muffling the speaker when you put it face up on a table. The volume or sound quality isn't anything extraordinary - it's merely average, however overall it provides satisfying sound.
Con New charging port isn't backwards compatible
Old micro USB cables will not work with this device, meaning if you lose or break your cable you will need to buy a new one instead of using an old cable you had lying around. If you need to top up your phone away from home, it will be much harder to find a suitable cable initially.