There are some great apps that will be able to take advantage of the N5s great hardware.
People sometimes say the original N5 launcher is slow, and doesn't take advantage of the hardware well enough. This is why I got Nova Launcher (Free for now, will buy paid in a week.) It drastically improves the speed of the device, I mean it's so fast I accidentally click random things because my fingers and eyes don't stay coordinated with it's staggering speed!!!
For my music needs I currently torrent all of it, but once Google Play Music Service comes to Canada, legally, I will be getting that for sure. But back to the music, I currently use uTorrent on my phone, and download music directly, then use ES File Manager to unzip the files, and then my music player of choice is PowerAmp, there is a free trial, but I paid for mine.
For Text Messaging/Calling I currently use Contacts+ as my regular SMS/Call app. It is aesthetically pleasing, and compliments the holo UI nicely. It also takes images for contacts from your facebook, instagram, and twitter followers/friends, so you're texting doesn't look plain.
For my Weather application, I find that the new Weather app, "Weather Underground" is the quickest weather app ever built. It finds information for you so fast and it has alerts built right into the app so you never have to open up the internet to read them! It also looks great and offers a notification icon with the weather in it. It also has interactive 3D and 2D maps so you can "get right into" the current and future weather conditions!
For my GPS application I use Waze because I speed alot when I drive and it's helpful to know where most of the police offers are, I'm kidding, or am I O_O, but really, Waze is a great navigation application, but it does use up alot of data fast, so.... get an unlimited data plan, I swear you'll love it!
People always ask about my battery widget, so for that I use Battery Widget Reborn. It's great feature is that it allows you to add a widget sort of thing into the notification tray and you can control your data, bluetooth, and even flashlight directly from the tray, so I don't have to go into settings all the time. It also gives you a battery in percentage on the top!
Also, lastly another cool app I love to use is "Screen Dimmer", it does exactly what its called. Basically when its dark sometimes my lowest brightness setting is still SOOOO BRIGHT on the N5, so I use this app to make it even less bright. The only bad thing about it is that since it doesn't require root, you cant use it to change the brightness of the software keys, so those stay white, and its REALLY noticable haha! Try it out though, it's useful!