Got an Echo Dot the other day. I've got a B&W A7 that sits by the kitchen and usually just plugged a phone directly into it, was considering a Chromecast Audio but the Echo Dot is just a more versatile tool. Perfect kitchen device, play radio, spotify, set timers, get the weather. Haven't looked into any other skills yet.
My main complain is that it doesn't have an optical out, the DAC is a bit crap and the A7 is wasted on it....it's not *awful* though.
No proper multi-accounts is annoying. Google Home has just added it and I think there are rumours Alexa is getting it soon. For now I have the other half's Spotify account linked, and I've switched over to Amazon Music Unlimited so we have them both set up (which is actually pretty good, bit cheaper than Spotify).