Unsurprisingly, where this speaker sounded best was on acoustic material and lighter fare. For example, the live acoustic version of Adele's "Turning Tables" sounded just fine and made me think I was listening to a larger speaker. I also found that it worked well enough as a speakerphone, though you'll want to keep the unit within a few feet of you when talking into the integrated microphone (Bluetooth speakers generally allow you to stream sound from a device up to 30 feet away).
The truth is I'd have no problem recommending this Rocketfish if it were cheaper. I understand there are certain costs involved when you include a lithium ion rechargeable battery (these types of batteries are fairly expensive), but the SPX15 just doesn't feel like it should cost $99 ($69 or $79 max would make it a more attractive buy).
To be clear, these is a decent enough product, but there are currently better options at $100 -- or even slightly less.