I’ve been on Sierra on my Laptop for a while now with no issues at all, but just discovered a feature which might make it more enticing to upgrade if you are a photographer.
The Photos app has changed the checkbox for devices. With El Capitan this device allowed you to “disable” opening photos per device, so the default for each device was to load and you had to check the box to prevent it from opening Photos when used. Unfortunately this only worked until you formatted the card again.
I noticed on m last trip that Photos wasn’t opening. I assumed it was because I use the card each day, download the images and continue to use the card until it’s full, then move to the next card (the images stay on the card until I get home and the data has moved through my chain of redundant backups). yesterday I went out to shoot, and formatted the card to start fresh, and noticed Photos didn’t open.
So the change appears to be in the Photos app the checkbox now says “Open Photos for this device” and its appears the default state is off. CF/SD cards now no longer automatically open the Photos app on my MacBook Pro when a SD or CF card is inserted.