If they don't bring over any of the new Lumia Camera features, go to the alternative camera apps. I've stopped using Lumia Camera on my Icon because it's just too slow. Sure, if you're taking scenery pictures or static photos where you have plenty of time to shoot, it's a good app. But if you have people who grew up in the iPhone age, they will complain how slow you're asking them to stay. Everyone wonders why they have to stay so still and why it takes so long for my phone to take a picture.
You'll miss a lot of moments when using the Lumia Camera app. Go to a wedding and try to take shots of the bride coming down the aisle. Chances are you'll get 2 shots and they won't be razor sharp (because of the slow focus time).
So my day-to-day shooting, I use ProShot because it's so fast and the manual features are set up like a traditional camera (I also use my Canon T5i when I really want spectacular pictures).
You'd be surprised how many great camera apps are out there beside ProShot. Heck, the one that comes from Microsoft gets better and better (it's fast but pictures aren't as good as Lumia Camera or ProShot).