Other times, she is mind-numbingly literal. One night during the N.B.A. playoffs, I asked, “Alexa, what’s the score of the basketball game?” She proceeded to give me a two-minute, 18-part definition of the word “score” that included “a seduction culminating in sexual intercourse.” Not exactly what I was going for.

And yet, after spending three weeks testing the Echo, I really kind of love Alexa. She is just smart enough to be useful. And she keeps getting smarter. This week, after a long invitation-only preview period, Amazon began selling the Echo to the public. At $179.99, Alexa is more expensive than I’d like. (Subscribers to Amazon’s $99-a-year Prime subscription service could buy the Echo for only $100 during the preview.) But if you’re the type who enjoys taking chances on early, halfway useful tech novelties, the Echo is a fun thing to try.

And if you’re anything like me, after a week with the Echo, you may feel the device begin to change how you think about home tech. It will not seem far-fetched to expect that one day soon, you’ll have an all-knowing, all-seeing talking assistant to control your lights, thermostat, entertainment system and just about anything else at home. In Alexa, Amazon has created the perfect interface to control your home; if it adds some more intelligence, it would be quite handy.

The Echo is a stout, plain-looking cylinder, about the height of a toaster, that you can park just about anywhere you have Wi-Fi access, though it seems most useful in the kitchen. It comes with a remote control that you don’t really need, because after a quick initial setup using your smartphone, you can control pretty much everything the Echo does with your voice. (The remote does have a microphone that allows you to speak to the Echo from far away.) From there, the Echo is terrifically easy to use — say “Alexa” and ask your question.

At the moment, there are only a handful of uses for the Echo. She’s great at telling you the weather, adding stuff to your shopping list, reordering items you frequently buy from Amazon, giving you a heads-up about your nearing calendar appointments, and answering the most basic of search queries.