Should you buy the new iPhones or save some money and buy an older generation Apple smartphone? We take a look at the key features that'll help you decide.
As that suggests, several older iPhone models will remain available to purchase, tucking in below the 3D Touch-enabled duo for a knock-down price (relatively speaking).
Which begs the question: which iPhone is right for you? Allow us to help you decide...
WATCH: What's new in iOS 9?
Why you should buy it: Small screen, stylish design, cheapest price
The latest iPhone in the Apple smartphone lineup is a familar beast. The SE is basically an iPhone 5S, with the insides of a 6S.
Those with small hands, those who like their phones to take up minimal pocket or bag space, and those who depend on easy one-handed usage will all find the iPhone SE's 4-inch display much easier to handle than the 4.7-inch and 5.5-inch alternatives.
It's also ideal as a gym buddy. Small enough to fit in your pocket without being noticed, but with plenty of fitness features and apps.
Yet, it has the same 12MP camera with 4K video recording and snappy A9 CPU paired with 2GB RAM as its bigger brother
Related: iPhone 6S vs Samsung Galaxy S6
What's more, with prices starting from £359, this is by far the cheapest iPhone model out there. To illustrate how cheap this is (for an iPhone), the top iPhone 6S Plus model starts from £619. You could buy an iPad mini 2 with the money you'd save.
Somewhat perversely, despite being the cheapest option, there's an argument to be made that the iPhone SE is also the most handsome and stylish iPhone in the entire range. From the iPhone 6 onwards, Apple has reverted to a somewhat bland, rounded, dare we say flabby design.
The diminutive iPhone SE, by contrast, is all right angles and bevelled edges. It's a beautiful bit of kit.
Selected deal: Three is offering the iPhone 5S on a 24 month £32 contract, with an initial payment of £9. For that you get 4GB of data, 600 minutes, and unlimited texts. Or, you can half that data allowance for unlimited calls.
Why you should buy it: Current design, strong camera, Apple Pay
The iPhone 6 has been superseded as Apple's top dog, but it's by no means obsolete.
For one thing, its design remains as fresh and relevant now as it did a year ago - and will do for another year to come. Why do we say that? Because it looks identical to the iPhone 6S. Seriously, this is real spot-the-difference stuff.
In fact, considering the iPhone 6 is noticeably lighter and slimmer than its successor, there's a case to be made for it being the nicer to hold and easier to lug around of the two.
Also, the iPhone 6 still has a great camera. For all of the iPhone 6S's added megapixels, early reviews of the iPhone 6S camera suggest that it doesn't represent the leap forward in image quality that we've seen across previous iPhone generations. A large part of that is because the iPhone 6 camera remains one of the best in the business for quick, accurate point-and-shoot snaps.
The iPhone 6 also saw the debut of Apple Pay, so combined with its new lower pricing (which starts from £459), it's the most affordable entry point to Apple's burgeoning mobile payment system.
If you want a compact iPhone that won't leave you destitute, but that looks and (in many cases) performs like Apple's latest model, look no further.
Selected deal: Carphone Warehouse is offering the iPhone 6 on a 24 month O2 contract with no up front fee for £36 per month. This will get you unlimited texts and minutes and 3GB of data. This deal is only going to last until September 30, though.
iPhone 6 Plus
Why you should buy it: Large screen, biggest battery, competitive price
There are those who say that the iPhone 6 Plus was the real new Apple flagship device of 2014, and that the iPhone 6 was just a compromised half-way-house to help quell the unease of the timid iPhone traditionalists.
We wouldn't go along with that viewpoint, necessarily, but if really large screens are your thing, it's a valid position to take. People love phablets, and the iPhone 6 Plus is Apple's most affordable phablet
Its 5.5-inch 1080p display is bigger and sharper than the brand new iPhone 6S, showing apps and games off in full detail. It also has the largest battery in any iPhone (2,915mAh), and it'll last you deep into a second day of normal usage.
Related: iOS 9 problems and how to fix them
All of this, and it's now available for a price that doesn't make your eyes pop out on their stalks. The iPhone 6 Plus can now be picked up from £539 - that's £80 cheaper than its iPhone 6S Plus successor, despite it offering a very similar experience.
If you want the large-screen iOS experience without breaking the bank, it's the iPhone for you.
Selected deal: Carphone Warehouse currently offers the iPhone 6 Plus on a 24 month £45 Vodafone contract with no up front charge. This will get you a meaty 6GB of data and unlimited texts and calls.
Why you should buy it: Fastest performance, 3D touch, stronger
The iPhone 6S is Apple's flagship phone. You know that as well as we do. But you might not have thought about how exactly it compares to the rest of the current iPhone range.
It's the fastest performer, for one thing. It comes packing the A9 CPU and 2GB of RAM, which provides a 70 percent performance gain over the A8 chip that powers the iPhone 6 and iPhone 6 Plus (not to mention the new Apple TV).
We count the iPhone 6S Plus in this equation, by the way. Apple's latest phablet might have the same processor and RAM allotment as the iPhone 6S, but its more pixel-dense display demands more of those components. Sure enough, early benchmarks suggest a slight performance advantage for the iPhone 6S.
The thing that really sets the iPhone 6S apart from all but the iPhone 6S Plus, though, is 3D Touch. This clever piece of technology detects how hard you're pressing on the screen, and ties in with iOS 9 to open up new, intuitive UI shortcut options. It's the feature most likely to prompt a legion of Android imitators in future, we'd say.
Finally, the iPhone 6S is the best choice for those worried about the fragility of previous models. The iPhone 5S's bevelled edges are ding magnets, while the iPhone 6 and 6 Plus went through the whole 'Bendgate' scenario that saw some handsets warping under everyday pocket pressure.
The iPhone 6S is built of sterner stuff than all of them. It utilises a much more rigid 7000-series aluminium, which is 60 percent stronger than the old material. Also, its display is made from Ion-X glass, which Apple reckons makes for the toughest smartphone display around.
The iPhone 6S isn't cheap, starting from £539, but if you demand the absolute fastest performance in a package that remains pocketable and manageable in one hand, it's your best bet.
Selected deal: Vodafone is offering the iPhone 6S on a 24 month contract with a mere £19 up-front charge. For £54 per month you'll get unlimited texts and calls and 8GB of data, as well as 12 months of Netflix.
iPhone 6S Plus
Why you should buy it: Top model, best camera, most advanced screen
Picking the iPhone 6S Plus means opting for the bleeding edge of Apple design. It's the single most feature-packed iPhone available.
It comes with the advanced 3D Touch input system highlighted above in the iPhone 6S section, but it also has a larger and significantly sharper 5.5-inch 1080p display. It's the best iPhone screen you can get, in other words.
The iPhone 6S Plus also has the best camera of any iPhone. Yep, even better than the iPhone 6S. While it has largely the same camera unit as its smaller brother, only the iPhone 6S Plus has optical image stabilisation (OIS) technology.
This means that both stills and (for the first time) videos are kept blur-free, and low-light shots are also boosted as a result.
Related: iPhone 6S Plus vs iPhone 6S
Of course, you'll have to pay a premium for these additional components. The iPhone 6S Plus is the most expensive model of the lot, with prices starting from £619.
The iPhone 6S Plus is the one to go for if you demand the most advanced and fully featured device in the range, or if you want the best image and video-capturing performance that Apple can provide - Money no object.
Selected deal: O2 lets you pick up the iPhone 6S Plus on a 24 month contract for just £9.99 up front, and pay £51 a month for unlimited texts and minutes and 3GB of data.
Still need some advice on the best iPhone to go for? Let us know in the comments section below.