Reviewers are not impressed with the fingerprint sensor on HTC's newest smartphone

The One max will recognise up to three fingerprints, these can then be assigned to either unlocking the phone or starting a key number of applications.

In practise we found the process to be a little sluggish, whilst the setup is arguably much easier than that on the iPhone - you only need to swipe four times - this does however mean there's little room for error so you have to swipe the whole of the fingerprint across the reader otherwise it won't simply won't recognise it.

This becomes frustrating when you're in a rush and downright infuriating if you're trying to unlock it one-handed. Whilst we commend HTC for implementing a technology that absolutely should be heading to smartphones we're not so sure whether this first outing has worked 100 per cent.

The fingerprint sensor on the device is unique to this HTC device, though. Positioned on the back, HTC said it is easy to swipe your index finger on the back after you hit the power button on the right edge of the phone with your thumb. (That is, if you are a righty.) However, unlike Apple's TouchID in the home button that just requires a basic tap, you have to swipe your finger quite slow for it to log you in.

When I tested the reader out on a pre-production unit it took a few tries to get logged in and because my hands are on the smaller side it was hard for me to then maneuver to then start using the phone with just one hand.

Using the One max in the recommended way — as a very generously proportioned phone — is an exercise in frustration, and nothing exemplifies that better than its major new feature, the fingerprint scanner. Firstly, it’s placed in exactly the wrong place. Sitting immediately below the camera lens and requiring a swipe, it pretty much compels you to smudge the lens every time you want to identify yourself. The need for a vertical swipe is also problematic, since your hand’s natural position is at an angle to the sensor, demanding an unnatural and uncomfortable motion to activate it. Inevitably, that leads to regular failures to recognize your epidermic signature.

Equally enervating is the fact that you have to wake the One max from sleep before swiping to unlock it. The whole point of these fingerprint sensors is to speed up security processes, not make them more finicky, and that’s exactly where the HTC One max fails. There’s plenty of potential here, as you can enroll up to three different fingers and assign each an app to launch, but that only works from the lock screen — why not universally? As it is, the fingerprint scanner implementation here is clumsy, awkward, and comfortably in line with the long history of failed attempts at making this technology work.

The sensor is positioned below the camera, apparently in the place where your index finger will naturally rest -- but it really depends on how you feel most comfortable holding such a large phone. It was in the right place for me, but my friend tends to hold phones lower down so couldn't easily reach the scanner. Once you do find it, it manages to accurately recognise the prints you've saved most times.

The implementation on the One Max is very different to Apple's option though, coming as it does on the rear of the phone in the more traditional-looking pad.

Sadly, that's where the similarities with Apple's offering end, as it's really rather poorly implemented on a phone of this size.

...For starters, it's in a really irritating place on the phone. OK, it's exactly where your fingers might rest, but that's also right below the camera, meaning you're never sure where you're sliding your finger, leading to a lot of missed swipes.

On top of that, the One Max is so large that you can't really get a comfortable downward swipe, as the phone requests you do, each time. This leads to an unlock accuracy that swings between 33 and 50%, which is enough to get quickly infuriating.

Compare this to about 80-90% accuracy for Apple's iPhone 5S, combined with the Cupertino brand's sheer brilliance at putting it in the home button, and you can see that these two devices are worlds apart in terms of biometrics.

The HTC One Max's fingerprint scanner will be as unused as that on most laptops and the Motorola Atrix, which is sad as it could have been a really nifty feature if it was in an easier to reach place.

The fingerprint scanner is built into the back of the phone and is activated by sliding your finger in a vertical downwards motion. In our testing, it achieved mixed results. One of the recorded fingerprints was consistently recognised more frequently than the others and even then the swipe motion had to be very carefully performed. It worked best when the phone was being held straight on in one hand.

As the sensor is located on the rear of the phone, directly below the camera lens, it was sometimes difficult to be sure you were swiping the correct element. The slight hesitation between swiping and the phone activating -- and frequently rejecting -- your fingerprint generally made the whole process of picking the device up to do something less seamless than it really should be.

Sadly for HTC, the scanner on the One Max doesn't even really compare in terms of accuracy and ease of use with the home button sensor on the iPhone 5s. It's perhaps ill-advised to take this tech on its first outing attached to the vast rear plate of such a big phone, where fingers are going to struggle to find it, never mind use it properly.

We've had about a 90 per cent success rate with the One max's scanner over the week we've been using the phone, but it takes some getting used to and we know that some others who had the device prior to launch didn't have such success.

Initially it's tricky to swipe the scanner without swiping the camera lens. There's little difference in feel between the two and they are only separated by about 6mm, but as time has passed, we've found the process has become more natural.

Rear-placement of interactive points on devices is a tricky business, something we noted with the Oppo N1 phablet that incorporates a touch panel on its rear.

But it's irritating that you have to press the standby button before you can swipe to unlock the phone, so it's a two-stage process and we'd much rather it was one.

Much as we hate to say it, the fingerprint scanner on the iPhone 5S is much better when it comes to unlocking: you press the button, it scans, and you're in. It's one process. On the HTC One max, we suspect that some will find it fiddly from the off, and disable the feature in favour of regular on-screen security.