I have owned a few of these and other small speakers. I prefer those with aux cords so you are not forced to use bluetooth and drain your battery. And those that you can use disposable or rechargeable batteries so you don't have to wait hours to use when a built in battery is discharged.
You will get up to about 15-24 hrs from the 3 AAA batteries depending on the volume level you use and the type of batteries. I use Panasonic rechargeable eneloop batteries and get the most hours from them.
This little speaker has amazing volume and sound compared to many this size. It is better than most and doesn't have as much of that "in a box" and tinny sound. Keep in mind, it is still a small speaker but you will will be hard pressed to find one better for the money.
The one disadvantage is that you have to be very careful with with the cord. It is very thin and will detach at the part below where it inserts into the headphone port. If it's stressed.
This is my second one. My first one that I've had for several years still works fine but the cord that plugs into my mp3 player is a little shaky now so I decided to buy another one as a backup. My mp3 player is not Bluetooth so this speaker is perfect. It's also compact (but still has robust sound) and not heavy so it's perfect for travel. I've been very happy with it.