We've had our Echo for several months now, and it's simply become an appliance in our kitchen.
I no longer set timers on the oven because it's simply quicker and easier to set one with the Echo.
I probably use it two or three times per home-cooked meal that I create to convert measurements: "Alexa, how many tablespoons are in a cup?" "Alexa, how many teaspoons in a fluid ounce?"
We're Prime customers and my kids are big Pandora and Spotify users, so after dinner there is a competition to see who will be the first to determine the music for washing dishes.
Probably the #1 thing we ask the device is for the weather forecast in the morning and again in the evening. This is info that we'd previously pull up on the phone or get from the news, but having it on-demand from the Echo is so quick and easy that we tend to just go to it first-thing.
I (and I alone in my house) like to hear the NPR "daily briefing" in the morning rather than watch the local commerci -- er, the local news.
My 8th-grade daughter uses the Echo with her homework to a middling extent. The definitions for vocabulary words, a summary of certain concepts from her Civics class, or even the definition of mathematics terms ("Alexa, what is 'the associative property of addition'?"). It's pretty good with this, but it's not a lot faster than typing it into a tablet or phone, and in the latter case you get text (more useful), not a verbal response.
Every once in a while, we'll use it to retrieve information that we would have Googled previously. "Alexa, what time does the Republican debate start?"
I think the biggest disappointment with the device is with our music library. 90% of the stuff we own was bought through Apple or else ripped from our old CD collection and stored in iTunes, which does not integrate "natively" with the Echo. My eldest daughter slaves the Echo to her iPhone through Bluetooth and plays the music that way (an escalation in the dish-washing music wars), but it would be a lot nicer if we could ask for artists or songs the way we can wih my (piddly) Amazon Music library.