I'll keep this short. As a pair of bluetooth on-ears without noise-cancelling turned on, they sound quite excellent and the ambient sound is noticeably lowered. The bass is certainly boosted, but not excessively so. Mids are not intrusive but clear, and the treble is good and crisp (to my ears anyway).
 
Turning on the noise cancelling definitely cuts out a significant layer of outside noise, but at the cost of shedding some bass and slightly thinning out the overall sound. However, you hardly notice it once you've had them on for a few minutes, and everything sounds normal.I've found that running them with NC off gives me the best experience.
 
The app is clever and gives you lots of control over sound variance, and the soundstage section adds a degree of fun, but you'll quickly find yourself defaulting to the default setting, which gives you the best, but not widest spread.
 
I've had these for a few months now, and they are a top notch pair of headphones offering a very rich sonic experience. they're very comfortable albeit a little heavy on the top of the head at first, but you soon get used to it.
 
Although I've missed out nearly every one of it's great features, for a pair of BT headphones I have to say they are well made and as good as I've personally heard in the past few years. One really nice touch is that when you take them off your ears the music automatically stops and starts again once you put them back on.
 
Well worth a road test and these days you can find them often on sale under $300.

To quickly set the scene, I've never really spent much on iem's of any nature until recently, and still probably only have one high-end pair to speak of (Sennheiser ie8's), but part of my recent quest for in-ears has been split between commuting and exercising. And it is this second area that brought me to trying out the Plantronics Backbeat Go 2's.
 
These in-ears are part of my long hunt for the perfect pair of iem's to accompany me only my daily morning ride (roughly 18 miles). And because I ride when listening to music, I am always cursing wind noise and lack of bass response that many a pair of iem's create when out and about.
 
So, introductions over, let me share with you the highs and lows that I have discovered over the past few months with these wire-free puppies.
 
Good facts:
Build Quality - is excellent. Everything is well made and feels sturdy. Three months of active usage in pockets, charging case and out 'n' about haven't had any impact on their wear and tear - they still look new.
 
Comfort - The Backbeat 2's are light on the ears and generally pretty comfy insofar as you tend to forget you're wearing them when out and about (I do imagine wearing a long time would be more noticeable than a wired pair due to their additional weight, but equally there's no chord to drag on them). Head movement of almost any amount, however vigorous does not dislodge them - thanks to each bud having a small transparent lug on them the fit is very secure without being noticeable.
 
Sound - They are surprisingly good to my ears. There's a decent amount of bass without being overbearing (certainly more than I've seen in many iem's), and both mids and highs can all be heard clearly, offering a slight bright edge (to my ears at least). They are by no means audiophile quality, so you will detect a degree of roll off, but not excessively so.
 
Charging case - Although this is an optional accessory (adding about £20/$20 to the price), not only is the case well made and a good protective unit, it incorporates a built-in battery and mini-usb lead to recharge your phones on-the-go, dispensing enough juice for an addition 2.5 charges - theoretically equating to about 15 hours of listening pleasure. Similarly, when needs must, because of the built-in cable, it'll actually add charge to pretty much anything else that draws power from a mini-use port.
 
Controls - They ship with a 3 button controller which isn't the standard iPhone variant - so you have to use the + and - buttons to move the tracks forward and back (no double/triple pressing on the middle button). Volume controls are easy to use, and will go way above what most people will want. the controller is well made and doesn't misbehave or fail to respond.
 
Making calls - as it comes with a controller and mic, I should mention that calls sound good and the mic is no better or worse than most that ship with wired alternatives. wind is the natural enemy, but indoors my calls are always clear to the caller.
 
Pairing - like most modern accessories, pairing is simple. I have an iPhone 5s and an iPad - both work well with it and switch when needed. It can pair up to 8 devices in all, but I've never had more than two in order to prove this.
 
 
Bad facts:
Size - Although a minor issue, because the battery and BT elements are built into the buds themselves, they do protrude a little, making them less discreet than other in-ears.
 
Wind Noise - More of a challenge however is that this larger 'bud' means that when moving about, wind noise is almost impossible to avoid, marring the general quality of audio being transmitted within. It's not a deal breaker, but if you're used to anything remotely like Etymotic er4's or HF3/5's then your day just got a bit worse.
 
Battery Life - Described by Plantronics as lasting beyond 4.5 hours, my own experience would put this closer to 3-3.5  hours. Again, if your on a long journey, you better pack a spare pair of wired buds too. And as handy as the charger case is, you can't listen to the headset whilst it's being charged.
 
Conclusion:
I've owned a few BT headsets in the past and these are by far the best ones so far.  Overall sound is enjoyable, and the bass is never wholly lost - even in windy environments. They won't trump wired sets like the aforementioned Ety's, but what do you expect for £67! They are a little on the big side, and although the charger case is a great idea, the built-in battery life is not as good as other makes out there, but fortunately enough for a 30 mile bike ride.
 
Would I recommend them? Yes. At £67 with charging case, they represent great value for money and have definitely convinced me that bluetooth headsets can now offer more than just a cordless benefit, packing decent sound - even without Apt-X.
 
Final note: I've just ordered the Sony SBH-80's, so will update this review once I've had a chance to compare them against the Backbeat 2's in a mini BT IEM shoot-out.