I bought this mp3 player for the size and, of course, the price. Can't beat 30 bucks. Don't expect apple or samsung quality, though. The user interface is not terrible. You do have to navigate through menus to get where you need to go but doesn't take long. There are a few extras: pedometer, stopwatch, timer, radio, recorder (haven't tried any).Now the music part, which most people buy this for (I think), it's not bad at all. At first, I was worried about sound quality. The first few songs I played sounded distorted or with static/white noise and I'm not usually picky with sound quality. After the 4th or 5th song it got better. I was thinking that maybe it was my bluetooth headphones but I switched to another pair and it was about the same.Speaking of Bluetooth, pairing is a little strange. In the main menu there is a BT icon that you select and it gives you the option to search, pair or connect/view connected devices. Setup is easy but kind of slower than what I am used to. After pairing my headphones, I went to "pictures" icon and after selecting it the player asked me if I wanted to disconnect BT. I was confused. I guess it can't multitask....But not a problem. 99% of its use will be for music.After loading music on a micro sd card, I went to "music" on the player. There was only 1 song that came with the player. I didn't try turning it off or on. Instead, I went to the main menu, "folder", "card folder", then my music folder where I stored all of my songs. I played a song and after that the player knew the location of my music. Now I can just go to "music" and all of my songs are there.I'm a "shuffle" type of guy. I listen to whatever comes on, of the 500+ songs I loaded on there. I know people complain about the navigation on this thing. It's not terrible but I don't go album to album, or artist to artist. That may be an issue for you if you are used to the convenience of apple, samsung, or other user-friendly interfaces.Overall, this is a great mp3 player. It does play videos, which I can't remember the format that it supports (it's not a common one that I ever use) and it has plenty of features that I will probably never use. The size is perfect. It weighs nothing, very light and solid feel. The card slot on the side isn't bad, the micro sd clicks in and out and the card does not hang out of the slot. Definitely worth the price. 4.5 stars!Note: I had issues at one point with my bluetooth headphones. I noticed the right side was not playing. I disconnected and reconnected and problem solved. I was impressed with the BT range. I went about 100 to 110 feet before losing connection, through a cinder block wall. I haven't tried running or exercising, yet.Update, one week of use: mp3 still working great. I have realized that sound quality is bad on many songs stored on the memory card. I will test the music off of my phone and compare. I don't see why copying mp3s would cause a drop in quality. It has never happened to me so I'm going to point at the mp3 player. But it's not random. It's the same songs every time. Also, certain songs will only play on the left speaker of my headphones. Not sure why. I have tried three different headphones and same thing. Might be a software issue. I'm still sticking with 4 star rating. Battery life is about 6 hours at 70 to 80% volume. Since the sound comes from the headphones, I'm not even sure that the volume on the mp3 player affects battery life. But who knows. I have 3 main sets of headphones that I use with the player and all of them maintain great connection with the player.