Update: The iPhone 7 is likely just weeks away, so those looking for a new iPhone may want to hold off on a buying decision until then. For those who currently own a 6S, you can now get a beta version of the new iOS 10 update on your handset.
Apple's tagline for the iPhone 6S is 'the only thing that's changed is everything', highlighting that the brand knows this is a phone that looks an awful lot like 2014's model.
It makes sense that Apple would try its hardest to show that, despite the handset looking identical to the iPhone 6, there have been loads of changes under the hood that make this an attractive phone in its own right.
The chassis is stronger, the camera sharper – with a new Harry Potter-esque way of capturing your snaps – and there's even a completely new way of interacting with the screen. On paper, it's an impressive upgrade.
See the iPhone 6S in action in our video review:
But when it looks identical to the iPhone 6, people will be desperate to know if the iPhone 6S is enough of an upgrade to justify the price. While the upgrades seem great, is it worth going all the way up to the iPhone 6S, or would the 6 do?
In terms of raw price, we're in a weird situation now. Samsung and the rest of the Android crew have been slowly ratcheting up the price of their high-end phones to the point where they're actually eclipsing the iPhone 6S at launch.
While Apple put its phone into a market where the Galaxy S6 was significantly cheaper there are new boys on the block in the form of the Galaxy S7, LG G5 and HTC 10. Either way, the iPhone 6S has a lot to live up to.
In the UK you'll likely have to part with between £50 and £100 upfront to get the phone for £36-£38 per month (if you want a decent slug of data and minutes) with the 6S starting at £539 ($649, AU$1,079) for the 16GB model, £619 ($749, AU$1,229) for the 64GB model and £699 ($849, AU$1,379) for 128GB.
It starts at $649 if you're looking to pick it up off contract in the US, with the new $32.45 monthly cost if you're thinking of getting locked into Apple's yearly upgrade plan.
In reality though, the question of who this phone is aimed at isn't that hard to answer: for most people stuck on the iPhone 5S it's clearly the upgrade they're considering, although the recent arrival of the iPhone SE will surely tempt some of those users who want to stick with the smaller form factor.
Beyond that there's the disgruntled Android owner who's tired of looking at the slicker app experience Apple offers and seeing their own handset looking sketchy in comparison.
(Of course, there are a few people that tried Windows Phones as experiments, but they'd probably be happy with just about any other phone if they're still using a Nokia Lumia 930).
The issue Apple is trying to solve with the iPhone 6S (and the 6S Plus) is how it can convince users, especially in a market saturated with really rather brilliant smartphones, that the 'S' variant of the impressive iPhone 6 is a worthy phone to upgrade to in its own right.
When something is so visually similar, the onus is on the brand to show that the upgrades are really worth the extra cash.
The iPhone 7 is just months away too, so unless you must have the very latest iPhone right now you might want to hold out just a bit longer. Why? The iPhone 7 is set to bring an updated design, more power and an improved camera. And if that doesn't float your boat the 6S will drop in price too, so it's win win!
The iPhone 6S is almost identical to the 6 in every way when it comes to the chassis. There are some very subtle differences, such as a slightly thicker frame and a little more heft, but it's so slight that I kept getting the two mixed up when doing side by side comparisons.
All cases fit both phones just fine too so, apart from a small S logo on the back of the phone, nobody is going to notice you've got the latest iPhone.
But there will be lots of you upgrading from the iPhone 5S, and in that case you'll need to be ready for a really big design change. The metallic chassis feels really nice in the hand, with a ceramic-like feeling on the outside (although if it's anything like the 6 then this can scuff over time if you keep it in a pocket with keys, so you'll need to think about the kind of case you'll want to keep it safe).
If you're not ready to take the leap to the new, bigger form factor, Apple has the new iPhone SE to satisfy your 4-inch cravings.
One of the things that Apple is touting is the fact the iPhone 6S is made of 7000 series aluminum, which is the strongest thing it's ever used in iPhone construction. The obvious connection people will make is with 'Bendgate', when some users claimed their new phone had developed a slight curve in their pocket without much pressure.
The common belief was that these phones began to twist when placed in a rear pocket and sat upon. While it was proven that other metal phones actually were worse when it came to bending Apple didn't come out of the controversy well.
So it's no surprise that, while the company won't admit the real reason, the new iPhone is strong and never going to bend with such pressure. However, I feel like that we shouldn't feel happy our phones no longer bend – this seems like one of the minimum expectations I'd have of a smartphone, not a compelling reason to buy it.
The front of the phone is now covered in a new level of strength, with a glass that's far less prone to shattering when dropped on the floor – now that's something I can get behind. We've not drop tested it - we'll leave that to some other, braver reviewer - if the screen is stronger the responsiveness hasn't dropped.
In the hand, the iPhone 6S still feels like a dream. Even with the extra 14g over the iPhone it feels lightweight, easy to manipulate and really warrants the price. Samsung's new Galaxy S7 Edge invokes the same kind of feeling, and with it you don't mind spending the extra money over a more budget phone.
In terms of design, if you've seen the iPhone 6 then you've seen the 6S. The volume buttons, the power key, the silencer switch and the speaker are all in the same place as its predecessor, with the grille at the bottom very easy to cover when you're watching videos or playing games in landscape.
If you're using the 5S, this is leagues ahead. The construction is good, the materials solid and there's no wiggle in the buttons at all. While you probably never bent your 5S, the idea that the iPhone 6S is stronger will probably please you, however unnecessary the claim is.
Apple's not done anything great with the design of the iPhone 6S, but the iPhone 6 was such a well-created phone that using the same chassis isn't going to harm its chances of success.
However, combined with the higher price and the continued presence of the iPhone 6, I wish we were at least seeing some retooling of the phone to make it seem more attractive.
The screen on the iPhone 6S seems to be identical to the iPhone 6's: we're talking a 4.7-inch affair with 750p resolution, which keeps it firmly in the 'Retina' range that the firm debuted all the way back with the iPhone 4.
It's hard to rate the display, as while it fails on resolution (quite spectacularly actually - phones a seventh the cost of the iPhone 6S offer 1080p screens, Samsung's cheaper phone has four times the resolution of the 6S and Sony has, inexplicably, launched a 4K phone) it doesn't drop too badly on performance.
The iPhone 6S display is clear, bright, laminated to the glass and insanely colorful. The first time I saw it on the iPhone 6 I thought it was a fake picture stuck on top of a dummy unit, such was the clarity on offer.
So to use the same thing on the iPhone 6S makes sense - after all, the lower pixel count means it can be thinner and the battery can last longer, thanks to having fewer pixels to drive.
But there are some things missing: for instance, the contrast ratio (the difference between the brightest and darkest parts of the screen) is still poor, with the black areas looking a little grey. Samsung's Galaxy range predominantly uses OLED technology, which offers 'true' blacks and high brightness and packs a much better visual punch, and would have suited the iPhone down to the ground.
The sharpness in side by side tests is clearly lower too - the 326 pixels per inch is very low even compared the 401ppi of the iPhone 6S Plus - and most other models are over 500ppi to bring really, really clear displays.
Given OLED technology is used in the Apple Watch - and admittedly it looks brilliant - it's a shame the same thing couldn't have been done with the iPhone 6S.
It's important not to get too hung up on screen resolution in a phone - after all, if it's not serving a purpose (hey, Sony?) then it's just wasting battery. But the industry has moved on, and the higher pixel densities on offer are starting to really bring something to the table, with apps and general use looking pin sharp.
Here's hoping the iPhone 7 makes a massive jump forward to join the rest of the pack.