As far as battery life goes, Monster doesn't seem to be promoting a number, so it's a little hard to tell how much you're supposed to get. It's supposed to last in the 6-hour range, depending on volume levels, and you can probably get closer to 10 if you're keeping things at moderate, background-music level. In that department, Jambox is the winner, promising 8 to 10 hours of battery life.
In terms of sound, the ClarityHD Micro is right there with the Jawbone Jambox and other models such as the Philips Shoqbox SB7200, Beats Pill, JBL Flip, and Jabra Solemate. You can quibble over which speaker has more bass (the Jambox may have slightly more) and which has more clarity, but they all play loud for their size, offer some bass, and have significant limitations. In other words, yeah, they play loud, but don't sound all that great, and tiny speakers can only perform so well.
When you play bass-heavy tracks through the ClarityHD Micro, it can handle it, but it will sound restrained. For instance, I ran some Swedish Mafia through the speaker and the music had a little punch to it but not a whole lot. The fact is the speaker's strength is in the midrange, so acoustic tracks and ballads sound best. Tracks like Fun's "Carry On" sounded good, with clear vocals and an overall clean sound.
It helps to put the speaker near a wall or a corner where two walls meet so you get some reflection. With all these little speakers, placement can help improve the sound, giving it a little more fullness. And I'll reiterate that you get little to no stereo separation with compact speakers because the drivers are so close together.
I may not sound incredibly enthusiastic about the ClarityHD Micro, but that's because I've had to listen to a lot of these tiny Bluetooth speakers, and the magic of hearing big sound (but not necessarily good sound) coming out of a small speaker has worn off for me. Still, comparatively speaking, the ClarityHD is a step up from an even smaller speaker such as the Logitech Mobile Boombox or the ball-shaped Sony SRS-BTV5 or the grenadelike Philips SoundShooter Wireless. Speakerphone performance is also good. Callers said they could hear me well, and they came through loud and clear on the speaker.
I'm guessing that the ClarityHD Micro hasn't sold terribly well, judging by the low number of reviews on Amazon. I think that's largely a reflection of its high price tag. It carries a list price of $229.99 that's really $199.99. But no matter, because anything more than $125 is too high. While the sound is very good for its size and the speaker is attractively designed, the build quality isn't robust enough for it to feel like a $200 speaker. And other products such as the $100 JBL Flip sound about the same.
The long and short of it is that this is a 3-star Bluetooth speaker at $200, but it would be 3.5 stars at less than $125. And that's really all it comes down to: price. So, if you can find this for less than $125 (at the time of this writing Amazon had it for as low as $113), it's certainly worth considering. But at any price over $125, it becomes harder to recommend with any sort of enthusiasm.