The Alexa support — which is available as an over-the-air update in the UE Boom and Megaboom apps — only works with Android devices for now, and is similar to the existing Siri and Google Assistant support built into the devices. It’s the full Alexa experience, although to activate it you’ll need to press the Bluetooth button on the speaker. (Unfortunately, it’s not the always-listening option that Amazon offers in its Echo and Tap devices.)
Still, it’s a useful addition to what are already great speakers. If you own a UE Boom 2 or Megaboom, the update should be rolling out now.