The future is here, Sony would have you believe, and it is really, really tiny.

The electronics giant aims to refresh its fitness wearables range with the latest Smartband model, adding heart rate sensing, physical notifications, and functional water resistance, all without sacrificing the sleek design from the previous version. Unfortunately, such lofty goals are undermined by buggy, inconsistent performance at almost every level.

I've developed a love/hate relationship with Sony's Smartband 2 in the three weeks I've been using it. As someone who doesn't normally wear a watch, I was impressed with how comfortable it is, its silicone band soon forgotten as it holds the main device snug against my wrist. It's pleasing to the eye, the smooth black featureless strap passable for a fashion accessory at a glance (and with the band itself available in multiple colours, it easily can be).

The comfort factor is a good thing, too, as this is designed to be worn 24/7. The main reason is to monitor your background activity, most notably sleep levels. As the amount of sleep people get is increasingly a focus of health studies, that's no bad thing, and it seemed to accurately record my sleeping state and duration each night.

The robustness of the Smartband 2 is equally impressive. It's survived several rugby training sessions and a proper match, and multiple swims. Sony has certified the device as waterproof to IP68 standard, which officially means it's fine in fresh water, up to three metres deep for 30 minutes. It's good for "casual use" in chlorinated pools (where the vast majority of people will be swimming) as long as it's rinsed afterwards. In practice, it's survived at least one 40 minute pool swim with no ill effects. Safe to say, if you treat the Smartband 2 right, you don't need to worry about breaking it mid-workout.

So, on a comfort, durability, and passive monitoring level, the Smartband 2 more than earns a pass. For a mid-price gadget(expect to pay around £100, depending on retailer), that's not bad.

Unfortunately, what is bad is the actual fitness tracking You know, the main thing you want a fitness tracker to do. It will make you more active, though: n the first four hours of using it, I somehow managed to walk 828 steps, all without leaving my desk. Even better, it revealed my unknown somnambulist tendencies, racking up 1,227 steps one night. On the other hand, all this increased activity is apparently a result of terrible accuracy.

To be fair, there's yet to be a fitness tracker or pedometer that's 100 percent accurate, but the figures the Smartband 2 was delivering were extraordinarily off-base. What makes that more frustrating is that the majority of its functions are actually controlled by its companion apps. The core widget itself, a nary inch-long speck of white with the sensor embedded in it, lacks any display beyond a trio of LEDs and has no input other than a single button. All of its settings, from alarms to notifications, are governed in-app. It's mind-boggling that you can't flick a setting to say you're sat at a desk and not to count rogue steps, or that it can detect when you're asleep but not be well-programmed enough to ignore "steps" taken in the same period.

Similarly, heart rate tracking seemed unreliable. Take a session on an elliptical -- using the grip sensors on the machine, my max heart rate would be detected at around 168bpm. The Smartband 2, once it synced data over, would max out around 125bpm. Other times, it would hit that figure as I was walking down the street, without feeling even slightly out of breath. I can't trust which, if any, of those figures are even close to accurate, though I'm fairly sure I get more of a workout on a cross trainer than going for a stroll.

Another constant frustration was connectivity. Considering it supports Bluetooth and NFC, that really shouldn't be a problem. Yet it routinely took several minutes for data to sync between the wrist-borne gadget and the monitoring apps. Twice, it simply refused to sync at all for over 30 minutes, corrected only by uninstalling and reinstalling the apps. All too often, the phone would know the Smartband 2 was correctly paired -- the device status is constantly presented on the notification dropdown -- but the app would persist in displaying an increasingly maddening "Disconnected". This occured on two handsets the Smartband 2 was tested with, a Samsung Galaxy Note II and a newer Moto X.

The last major frustration was having two apps to use with it in the first place. Admittedly, Lifelog is an optional install, though it promises more intricate reports of the data gathered than the mandatory Smartband 2 app. Either way, it seems like needless bloat, and a resource hog for the phone. The Note II's performance in particular dropped notably, and although it is almost a three years old, it meets the Smartband 2's system requirements.

There are other, tertiary functions the Smartband 2 pulls off well. It can function as a remote media remote, playing, pausing, or skipping tracks back and forward with simple multi-tap controls. Its vibrating alerts for calls and texts are a nice touch, when the phone and band maintain connection. Being woken up by a gently intensifying vibration on your wrist proves supremely preferable to a blaring alarm shocking you to life in the mornings. There's good technology at work here.

Unfortunately, it's just not reliable enough. When you're getting such wide discrepancies in data as the Smartband 2 tends to deliver -- when you can get it to deliver at all -- the results are meaningless. Ultimately, what use is a fitness tracker that can't actually track?