In many respects, you know exactly what you're getting from an HTC flagship phone even before it lands.
This time around, though, alongside mainstay 'sells' such as a premium aluminium build and the HTC Sense custom skin, a few major changes are afoot.
Not only will we get two versions to choose from, there's a completely rethought camera to look forward to and a major display upgrade.
Keen to find out more ahead of the M9's debut at Mobile World Congress next month? You'd best stuck in then...
1 Similar design
According to leaked pictures, HTC's next flagship will look very similar to its current one. That means the same all-metal unibody design that won us over last spring.
That's no bad thing: the One (M8) was one of the plushest handsets of last year, and made the Samsung Galaxy S5 look cheap in comparison.
Indeed, Samsung's move to metal mobiles is most probably down to the superior stylings of the HTC One (M8) and iPhone 6.
Still, anyone craving a radically different look might be disappointed.
2 Completely different camera
It's all change on the imaging front, however. According to an HTC ROM developer, the One M9 will have a completely new camera.
It's said to boast a 20-megapixel snapper with a Toshiba T4KA7 sensor.
This is a radical departure from the 4-megapixel 'ultrapixel' snapper found on the HTC One (M8).
HTC made a big deal of this at the One (M8)'s launch. Its pixels are bigger, so let in more light which gives better performance in poorly-lit conditions.
Now it looks like it's abandoning the tech and joining the megapixel arms race.
The One (M8) did feature a duo mode, which let you change the focus of the picture after you'd taken it.
Hopefully HTC has some more snazzy camera features up its sleeve.
3 Better Wi-Fi performance
According to the same HTC ROM developer, the One M9 will feature the same wireless module as the Nexus 6.
The Broadcom BCM4356 wireless module supports Wi-Fi 802.11 a/b/g/n/ac and Bluetooth 4.1, and should ensure the One M9 has superior Wi-Fi skills than its predecessor.
4 Two versions are incoming
The HTC One M9 is a given, but rumours suggest a bigger version is also on the way.
Called the HTC One M9 Prime or Plus – sound familiar? – it's said to boast a 5.2-inch Quad HD display.
That should shame the standard One M9's 5-inch 1080p screen.
Though other rumours throw this into doubt – the One M9 is also said to have a 5.5-inch Quad HD screen.
Considering the trend towards bigger and sharper displays, we'd think HTC would opt for a Quad HD screen for the One M9, and just increase the size for the One M9 Plus.
But time will tell.
5 Android Lollipop
This one is a dead cert. Despite launching at the end of last year, Lollipop is on just 1.6 per cent of all Google phones and tablets.
That's ridiculously low, especially compared to iOS 8's uptake of 72 per cent.
Nevertheless, any new phone worth its salt will launch with Lollipop, and we'd expect the One M9 to be no different.