Alexa (that's the name of my Echo, but there are only two name choices... I'd bet that will change) plays any song I desire, and has excellent sound quality. So I now have a big, obsolete Bose radio/CD player sitting here gathering dust (anybody want to make me an offer?), as well as quite a few CD's I've collected over the years that I don't need. I also have an Internet radio I bought several years ago so I could listen to my Pandora stations while I was going to sleep. I don't use it any more, and would gladly give it away to the first local taker. You have to have Wi-fi to use it, of course.
Because I pay for Amazon Prime ($100 annually, but if you have a student in the family it's much less), I can listen to almost any song you can think of, free. You can make a list of a bunch of songs, name the list, and ask Alexa to play it at any time. I no longer buy songs. I can listen to my Pandora stations, as well. One big perk in Amazon's favor is, of course, that the Echo is useless unless you pay for Prime. I had Prime already, because prices are usually as cheap as any and cheaper than most, it's usually free shipping, and there is NO TAX on purchases. If you're buying something like a computer or an exercise bike, that is HUGE.
Alexa will read my Audible books aloud. Originally I thought she would be reading them in her robot "Alexa" voice, but no: She reads them as they are supposed to be read. I can get Audible books over the Internet from my library, too, so no need to spend money on those. I can listen to any radio station anywhere... there's a list of all the local ones. Who needs a radio in the house? Yes, you can do these things on your computer, but with the Echo, you can give commands when your hands are in dishwater or biscuit dough; no need to stop, wash your hands, wait for the computer to wake up. You get the picture.
Of course there's my grocery list. "Alexa, add celery to my list." Voila!
There are pricey items to install that will allow you to tell the Echo to turn your lights off and on, even when you are away from home (using your Ipad or phone). I don't need that skill, but I can see where it would be handy for some people. You can also turn your heat and air conditioning up or down in the same way.
It's possible to ask the Echo to order things from Amazon, but I prefer to do that from my computer. There are untold fun things (skills) that she can be commanded to do; most of them are downright silly ("Alexa, Simon says..." and she'll repeat whatever you told her, or "Alexa, tell me a joke").
If you have Google calendar, she will tell you what's on your calendar when asked. I often ask what the temperature is before heading outside. She can do the most complicated math problem you want to throw at her, so there's no need to have a calculator around. All this, remember, is hands-free.
Believe me, I've barely skimmed the surface. You can read a C-net review HERE. They don't rate the speakers as highly as I would, but I'm no sound snob.
I haven't met a single soul who's purchased the Echo who isn't thrilled with it. Even my husband likes it, although he prefers not to talk to her; he'll say, "Would you tell that thing...." And I do. It's a little like having a maid, one who won't be trying to steal my husband when my back is turned.