I'm upgrading to an iPhone 7 from a 5s; what do I need to know?

Hi. The main difference you'll notice, and it will seem huge at first but you'll get used to it quite quickly, is the larger size of the device. 3D Touch has been added since the 5S, this is a feature which allows you to press in harder on the screen, for example on an icon on your home screen, to bring up a list of shortcuts instead of opening the app. The home button is no longer a mechanical button, so it feels a bit weird at first but I actually quite like it and again you get used to it quickly. You'll also notice the device vibrates at times, for example when scrolling on a picker menu. Of course there is also the fact that the headphone jack is gone. Instead the EarPods in the box connect by the lightning connector. It also ships with an adaptor so you can still use your old earphones if you want. That's everything I can think of at this time.

Also you have 2 speakers and when you play music or voiceover it will vibrate,

If you want or need to do a hard reboot, you will need to hold the Sleep Wake button, and then the Volume Down button, not the Home button.

Honestly, you're gonna have more fun!

One thing you can do when setting the phone up is there is a screen that allows you to choose how pressing the home button feels. If you have someone else set this up for you, don't worry you can still get to this under settings/general/home button. there are 3 settings for how the home button feels when you press it, i'm going to call these light, medium and heavy. I have mine set to light, because that amount of feedback works for me, but you might like it another way. Also note that sounds is now sounds and haptics. You will get used to it right away and you'll have big fun.