Does anybody know how GPX mp3 players are? Planning to buy one are they good?

The GPX mp3 players are great. The only advice I would give is to not purchase the cheapest one you can find. Usually the best I have seen are in the $45 to $75 range. The lower priced GPX players are generally cheaply made and lack options. Good luck

Reviews are fairly good for this brand considering it is so cheap!
on average it receives 4 out of 5 stars!  here is actual reviews:
"Most people interested in a player like this are going to find 3 features particularly appealing: the price, the sd slot, and the use of AAA batteries. For me, it was the first two, and the fact that it doesn't have voice recording (at my new job, bringing a voice recorder or usb key can get you fired. Just try finding an affordable mp3 player that isn't either!).

Obviously, a low price is appealing to anyone. The sd slot is convenient as it allows one to swap out cheap cards full of different music and bypass the slow transfers to the limited two-gigabytes of on-board storage. And finally, the use of AAA batteries means you can keep a pocket full of batteries (rechargeables ideally) on hand and never run out of juice, and you also don't have to worry about an internal battery wearing out over time. Basically, you have a device that's both cheap and quite future-proof. At least, theoretically.

So, what to expect if you were to purchase one... first of all, you'll probably notice that it isn't terribly bad to look at, but once you get it in your hands, feel the weight and click the buttons, it seems quite cheaply built. I don't think I'd call it fragile, but it's definitely not what you'd call rugged. I guess it's no worse than I'd expect.

When you plug it into the computer it'll light up with the letters "USB", and Windows XP instantly recognizes it as a USB drive and you can immediately begin transferring files to the device. Fairly straightforward, though the transfer speed is a bit sluggish. However, here's where the serious problem I mentioned in the title and preface might crop up. If you look at the instructions on how to transfer files, it says that you should hit the "mode" button to switch to USB mode. As you are already in USB mode, hitting the button will put the device in "MTP" mode. You will then be unable to perform file transfers to the device, and there is no way on the device itself to return to USB mode. There is a solution (see the end of the review), though it is not something the vast majority of typical users would ever be able to figure out, nor was the solution particularly easy to find online (http://www.gpx.com was of no help). So, if you can help it, never hit the "mode" button while the device is plugged into a USB port.

Now that that ugliness is behind us, lets talk about actually playing music on the device. Getting it to play is rather quick and simple; simply slide the switch into the "on" position and hit play. The device works best as a random shuffler as there is no way to directly access the directory structure, but it does have a search function that allows you to search for songs by artist, song name, album and filename. So, it helps if your mp3 ID tags are all in order, but if not, you can at least name your songs appropriately (ie start all the Nirvana files with the word "Nirvana"), search by filename (pause, hold "mode" for a second, enter the name "NIRVANA", or at least the first few letters) and the player will create a playlist of all the files it finds starting with the letters you input. It's not exactly quick, the functions of the "mode" and "play/pause" buttons should have been swapped in this case, but it's manageable. Just don't do it while driving.

Once you start playing music, you might be surprised to find the player doesn't actually sound half bad. It's nothing to rave about, but there's nothing significant to complain about either. There's no hiss, the music is clear, it can power my Sennheiser HD 485s with decent volume and bass, and the equalizer presets allow some customization (the jazz and rock settings I like in particular). It sounds pretty good even at high volume, though when there's silence or very quiet parts of a song you might notice some  barely audible, squeely, electronic noises. For the most part, it's too quiet to be seriously detrimental to your enjoyment.

Operating the device is mostly intuitive, though the buttons could have been designed better. The on/off slider, which has a handy "hold" setting, is a bit touchy, meaning it's difficult to not turn off the device when sliding out of the "hold" setting. When changing the volume, it's easy to accidentally skip songs. Also, the mode button is used for four separate functions; while playing music, tapping it changes playback mode (normal, random, repeat, etc...), and holding it changes the equalizer presets. When you pause the device, holding the mode button goes into the search function, but tapping the button activates a function that apparently does nothing. It seems that it's supposed to switch between the internal memory and the sd card, but you actually can't access the internal memory when an sd card is in the slot. It doesn't seem to do any harm to change the setting, it's just pointless and a bit confusing.

Using SD cards is quite simple. Simply drop a bunch of music files on a card, plug it into the device, and it'll play files off the card as if it were the internal memory. I don't have a high capacity (SDHC) card to test it with, but according to a review on http://www.Sears.com they are supported.

As far as battery life, having just bought the product I can't really say, and different AAA batteries will have different amperages so your mileage may vary, but I'd estimate that a typical AAA battery would last about 6-7 hours at moderate volume. I'm also guessing that playing music of the sd card would drain the battery quicker, though it might not be a significant difference.

Overall, for the money the device is quite a lot better than I would have expected, especially if you take advantage of the SD slot and being able to swap out batteries. It's too bad they didn't build the device with a clip as it seems like a great budget alternative to the Ipod Shuffle."