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 for of the Galaxy S7, LG G5 andHTC 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 (US$649, AU$1,079) for the 16GB model, £619 (US$749, AU$1,229) for the 64GB model and £699 (US$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 aNokia Lumia 930).