In Defense of 3.5 Inches
This post is more or less in direct response to modilwar's excellent argument for a ~4" iPhone. It's not like Apple hasn't simply enlongated the screen like that before (see 5th gen iPod nano). But I'd like to make some counter arguments as to why keeping the screen at the same aspect ratio, at 3.5 (or maybe 3.7) inches is a good idea.
Consider this: eventually, Apple is going to double the screen resolution and thus the pixel density of the screen again. Moreover, it will happen sooner than you think (I would guess within five years).
A doubled resolution would situate the iPhone at 1920x1280 pixels, with 652ppi at 3.5 inches and just over 600 ppi at 3.7 inches.
That's exactly enough to display 1080p content in full, with 100 pixel letter boxes.
It's also enough horsepower, presumably by then, to facilitate linking an iPhone to a standard monitor and using it as a small computer. Imagine a dedicated interface on the phone accompanied by the advantages of a desktop display for surveying content. I think that by the time the iPhone doubles resolution again, it will also come with 64 or 128GB of flash memory standard, and apps will use a universal binary that allows a desktop UI within the app (useful for both Desktop and TV apps). Why - because Apple historically isn't afraid of solving the innovator's dilemma, it adds a lot of value to the Apple TV platform (which this Desktop universal binary would be marketed as a big part of), and it furthers the phone's claim to independence as of iOS 5 while still tying the user to Apple's closed ecosystem. This really could be your only computer.
Back to resolution: isn't 326ppi good enough? Isn't that print resolution? Not always, according to R.N. Clark, who makes a well informed argument about print resolution that is directly attributable to ppi:
Here, Clark notes that 600ppi is "noticeably sharper" in good light, with distances closer than 1 meter - which describes 100% of the instances where we use a phone with a backlit display. Will it be a big of a leap as the 3GS to the 4? Probably not. Will it be worth it? When the time comes, absolutely.
Now, the size and aspect ratio argument. If Microsoft has historically been concerned with software legacy (not as much with Win8, but that's another story), Apple's concern with iOS has been all about maintaining hardware legacy. They decided on a set of key UI design elements for their devices, and kept it consistent:
- a screen that is thumb-addressable to all markets (I actually think this is a major contributor to the iPhone's current Japanese popularity: keeping its size friendly to smaller hands while most other phones are blowing up)
- a single front-facing hardware button (not capacitive to mitigate accidental touch, and allow sightless operation)
- a single hardware port (proprietary for the accessory market, but also to prevent things like installing slow SD memory)
So, yes, this argument is kind of boring on face value, but it allows for some pretty exciting things to emerge, such as the Desktop interface suggested above. Apple has also historically waited until it feels it's the right time to implement an upgrade rather than find the technically most advanced component, arguably to the detriment/ compromise of Apple's hardware designs. The only exception has been the iPad (3), but I think most will agree that the compromise in size/ weight is so neglible it is barely worth a mention, and well worth the benefits. I also just don't think Apple will allow a period where most third party apps are letterboxed in the same of an enlongated phone, in a non-standard ratio no less. It worked for the Nano because it was a peripheral product with locked down software. Not to much with the iPhone (though I think it is a good idea, and makes a lot of sense in its own right).
So I think we're going to see Apple sit on this resolution and screen size for at least a couple years, focusing improvements on other things. When it's painfully pbvious that the screen is looking long in the tooth - like it did in May 2010 - then we'll see another doubling in resolution, with its unique benefits. Sounds crazy? Yes.
But it also happens to be the most logical extension of what Apple is doing.