So, I originally got an iPhone 7 at launch, but I decided to upgrade to an iPhone 7+, making it my first Plus iPhone. I decided to do it for my birthday and so that I could have the best phone possible when I decide to pay off my lease. I didn't think there would be that big a difference, but you can really tell a difference between the two devices I feel. I'm going to just hit the big differences I've found.
Size:
Honestly, now that I own a Plus and have had it for several days, I don't see what's wrong with the size. It doesn't feel any bigger in my hand than my old Note 5. I can still reach to the other side of the phone in one hand, and it still feels super comfortable. I guess there's nothing wrong with making it smaller, and I still prefer the smaller size of the 7, but I have no issue with the size of the phone at all.
Display:
I thought that the iPhone 7+ display would just be a slightly larger version of the 7's. However, I was wrong. the display is so much more sharper. On the 7, when I would look close, I could start to make out pixels, but on the 7+, no matter how close I get, I can't distinguish the pixels at all. I can barely tell the difference between it and my old Note 5, even though the Note 5 is higher resolution. The display also feels like it's brighter.
Camera:
So, they both have the same base camera, but honestly having two cameras is a really great idea. The zoom is so much better than on the standard 7, and Portrait mode is just so much fun. Yes, there are apps for the 7 that produce a similar effect, but none are as easy or good as the built in one using both cameras. It's been so much fun. I hope future versions of iOS expand on using the two cameras.
Battery:
This has been the most noticeable change. With the same amount of usage so far, the times of day where my 7 would hit 50% and 20% is when the 7+ hits 80% and 50%. I've gone over 24 hours without charging the 7+ and I still have more than 20%. It puts every previous iPhone and Android phone I've ever owned to shame. The battery alone has me committed to Plus models forever now.
Speed:
The only difference in speed is that the iPhone 7+ has 3GB of RAM, where the 7 has 2GB. The only difference I've noticed is that a few apps don't refresh as often. Tumblr is most noticeable. On my 7, leaving Tumblr after a few minutes forced a refresh, but on the 7+, it can stay in its state for MUCH longer.
The 7+ is such a great upgrade. I really wish Apple had kept the original philosophy they did with the 6 family, where the only difference was the battery and resolution, because if I could have had all of this but on the 7, I'd probably prefer the smaller 7. Still, the upgrade is so worth it. I'm not buying anything smaller now.
Size:
Honestly, now that I own a Plus and have had it for several days, I don't see what's wrong with the size. It doesn't feel any bigger in my hand than my old Note 5. I can still reach to the other side of the phone in one hand, and it still feels super comfortable. I guess there's nothing wrong with making it smaller, and I still prefer the smaller size of the 7, but I have no issue with the size of the phone at all.
Display:
I thought that the iPhone 7+ display would just be a slightly larger version of the 7's. However, I was wrong. the display is so much more sharper. On the 7, when I would look close, I could start to make out pixels, but on the 7+, no matter how close I get, I can't distinguish the pixels at all. I can barely tell the difference between it and my old Note 5, even though the Note 5 is higher resolution. The display also feels like it's brighter.
Camera:
So, they both have the same base camera, but honestly having two cameras is a really great idea. The zoom is so much better than on the standard 7, and Portrait mode is just so much fun. Yes, there are apps for the 7 that produce a similar effect, but none are as easy or good as the built in one using both cameras. It's been so much fun. I hope future versions of iOS expand on using the two cameras.
Battery:
This has been the most noticeable change. With the same amount of usage so far, the times of day where my 7 would hit 50% and 20% is when the 7+ hits 80% and 50%. I've gone over 24 hours without charging the 7+ and I still have more than 20%. It puts every previous iPhone and Android phone I've ever owned to shame. The battery alone has me committed to Plus models forever now.
Speed:
The only difference in speed is that the iPhone 7+ has 3GB of RAM, where the 7 has 2GB. The only difference I've noticed is that a few apps don't refresh as often. Tumblr is most noticeable. On my 7, leaving Tumblr after a few minutes forced a refresh, but on the 7+, it can stay in its state for MUCH longer.
The 7+ is such a great upgrade. I really wish Apple had kept the original philosophy they did with the 6 family, where the only difference was the battery and resolution, because if I could have had all of this but on the 7, I'd probably prefer the smaller 7. Still, the upgrade is so worth it. I'm not buying anything smaller now.

...It's all about the U, right?