Logitech's X100 is a "micro" wireless speaker that competes with such models as the JBL Clip and Divoom Voombox Travel. They're all similarly shaped (think hockey puck or doughnut), cost about $50 (you can find them for £40 in the UK or AU$60 in Australia), and produce bigger sound than their tiny size would indicate.
I like the hard, rubberized finish on this speaker and it seems fairly durable. It's got a little loop on the top that allows you to hang the speaker from a backpack or doorknob or whatever and you can also just lay it flat and have the single driver fire upward. It weighs a scant 5.6 ounces (159g).
Battery life is rated at 5 hours, which seems to be about average for this type of speaker, and it has speakerphone capabilities and an auxiliary input for non-Bluetooth devices. It charges via Micro-USB.
I can't tell you that this model sounds any better than its competitors, though it's arguably their equal. The Divoom Voombox Travel, for instance, plays louder but does distort at higher volumes. The JBL Clip is right there with the x100 in terms of sound (it distorts a little, too) and offers similar battery life and a "clip" for hanging the speaker on a backpack and elsewhere.
The X100 performs best with simpler tunes (with acoustic material, for example, it sounds quite decent) and makes a good companion for a laptop or tablet video watching -- it easily sounds better than the internal speakers on most portable devices. I thought it sounded fairly natural, with a reasonable amount of detail, and mostly managed to avoid sounding harsh.
Like with all these tiny speakers, it only outputs so much bass, so if you're looking to rock the room with some electronica or hip hop, it isn't going to cut it. But for casual listening it should leave most people thinking, "That sounds pretty good for how small it is."
For a little bigger sound, you can opt for the Logitech X300 , which retails for $70 in the US, £60 in the UK, and AU$80 Down Under. It isn't as portable as this one but it's still a quite compact and has multiple drivers.
There are a number of micro Bluetooth speakers out there, and at this point it's hard to declare a true winner in terms of sound quality. Some play a little louder, but they can also run into distortion issues when you take them past 80 percent volume.
In the end, the X100 is one of the better micro wireless speakers out there. While its sound is decent for its class, ultimately you'd probably want to pick it over its competitors because you like its design (I do) and maybe because it costs slightly less. Some colors can sometimes be had for closer to $40 USD, which seems more like what you'd want to pay for this speaker.