If you want a stereo Bluetooth speaker, the handsome JBL Flip (available in black and in white) is a great choice. It really moves air - translation: great bass - and doesn't distort even at the shockingly high max volume, suitable for parties. This unit uses a charger with an old-style round plug rather than a USB plug charger; this is frustrating, because it means carrying an additional cable. There are no track skip buttons; a minor point. Still, JBL is noted for high quality speakers, and this unit does not disappoint in that regard.
The Flip is a speakerphone as well as a speaker, but the sound on the other end is a bit muffled. Also, although you can answer the phone by pressing the phone button on the speaker, I found it was not possible to hang up the phone this way on the Samsung Galaxy S4. Presumably it will work properly with older phones; the S4 uses Bluetooth 4.0, and I'm guessing this is a compatibility glitch.
JBL also offers a unit at a higher price with similar sound but fewer features (no speakerphone): the JBL Charge, available in your choice of boring grey or fun lets-go-to-the-beach green or blue. Unlike the Flip, it charges using a USB charger; it also has a USB out charging port so you can use the unit to charge your phone. According to the specs, you get 12 hours of listening time from the Charge vs. 5 hours from the Flip. Perhaps that accounts for the price difference. Once again, the unit offers great JBL-quality sound. Also, both the Flip and the Charge have aux in jacks.
If you're looking for great sound, the two JBL units are solid choices that won't disappoint.
For more Bluetooth speakers, check out my Bluetooth speaker roundup. For other reviews (especially of devices for mobile, click here.
Disclosure: The manufacturer provided product for this review.