Bought two Dots for my granddaughters. They are smaller but do exactly the same thing as the bigger Echo. My daughter has the Echo and it is larger and the sound is better.
If you plan to use it primarily for music the Echo is probably better because it has a bigger speaker and better sound quality. Otherwise, the Dot is great. Plays music, talks, plays games, and will turn the lights off and on. But the wall switches are not cheap and they only work things which are plugged into them.
I decided against buying myself a Dot or Echo because I did not like how you have to shout at the device if you are across the room or in a different room.
Spent 2 weeks visiting my daughter and grandchildren and found all the shouting annoying. I could hear the kids yelling, 'Alexa, wake me at 6am.' 'Alexa, turn my light off.'
Their bedrooms are upstairs and you could hear everyone yelling at their devices. Not for me!