If you have been waiting for a Cortana enables smart speaker and in the US then you won’t have to wait much longer to wait. The Harman Kardon Cortana powered speaker called Invoke will be on sale this Sunday in the US costing $199.99.
The unit comes in white or black and has Cortana built it so you can use it to set reminders, ask question or control your music playback. Currently there isn’t any smart home integration in Cortana (which is what I use my Alexa Dot for the most) but Microsoft say that Nest, Philips Hue, Wink, and Insteon are supported via the speaker. Also coming is the link between Cortana and Alexa so you should be able to ask control devices via Cortana with Alexa.
I think this could be a hard sell compared to the Amazon and Google devices which has a much richer ecosystem. The Invoke will be available from the Microsoft Store, Best Buy, and HarmanKardon.com. No news when or if it will come to the UK.