The battery on the HTC One (M8) is proclaimed as 40% longer lasting than its predecessor, and that's something that needed to happen as it was one of the bigger sticking points of the old version.
To make that happen HTC has added in a 2600mAh battery and combined it with Qualcomm's more efficient Snapdragon 801 chip to make everything last a little bit longer.
On top of that, the HTC One (M8) will also be arriving with Extreme Power Saving Mode, which will allow users to keep their device in a very low drain scenario by limiting the data to only slip in when the screen is on, and allowing access only to the likes of calling, messaging and calculator.
We all need to do sums no matter how much power is left, people.
In practice, the claims actually hold a fair amount of water. The new One (M8) is much, much better at holding its power than last year's version, and a standby drain of 5% every two hours is more than achievable.
If you're looking at this purely as a business phone, meaning you won't be playing games or flipping about with apps or movies all the time, it's highly likely you'd only need to charge every couple of days, even if you use your phone regularly throughout the day.
The HTC One from last year is improved when it comes to battery (compared to when it first launched) with the new Android 4.4 KitKat upgrade helping things again. But it's only a good buy if you're constantly going to be near a charger each day, where the new phone is much more content being plug-free for longer.
The camera on both phones looks relatively similar from the outside – well, that is apart from the fact the HTC One (M8) has a large extra sensor on the top to provide depth to snaps.
This works by clicking in the millisecond you press the shutter key, embedding the metadata into the JPG to allow the handset to work out which areas are foreground and which are not – essentially giving the user complete control over the subject they're actually snapping.
The original device obviously doesn't have the same hardware, but both have the same Ultrapixel technology on board to make the low light pictures look great.
However, while both come in at around 4 megapixels in resolution, meaning zoomed pictures or those blown up on a large screen will look a bit muddy, the new device has a more efficient image processor.
This means, combined with the upgraded Qualcomm Snapdragon 801 CPU, images focus and save incredibly quickly, even to microSD storage.
The low light capability of both is still very impressive, but the newer phone understandably is a little more sensitive and can take more pictures at a faster pace.
That said, if you just want a camera that doesn't do more than just take generally good shots and you don't give a hoot about post-capture processing, the first One is a good choice still.
However, the new HTC One is a real step up and one that you should really consider if you're desperate to go with the Taiwanese brand but want to take the better snaps.
If you're torn between the HTC One from last year and the new HTC One (M8), then it's a very fine balance and really comes down to price.
The older version is a good deal cheaper now a newer version is on the market, and probably works out slightly better dollar for dollar.
However, do think about what you're signing up to if you go for the still-attractive older model. You've got a much stronger processor on the new device, which leads to better battery life and general use – it's less likely to slow down over your lifetime with it.
That said, the older model still has enough of a feature set to warrant being a viable choice, and is going to get similar software to the new device as well to keep it fresh.
So if you want to save money, 2013's One is a good buy, providing you don't mind no expandable storage, a lower-spec camera and a weaker battery.
The new HTC One (M8) is definitely going to be one of, if not the, phone of 2014, so if you want to make sure you've got one of the best options for the next 24 months, we suggest that's the device to plump for.
Check out our full HTC One (M8) video review: