Summary: let down by an apparent total lack of directory navigation, slow file transfer and sound artifacts.
Got this off eBay as a store return (listed as ex-display, but the seller had too many of them to all be from such a source) and after playing with it briefly I can see why so many have been taken back to Tesco. £8 is a reasonable price, but the £19.99 they're currently asking on their website isn't. It's also known as the Technika MP407 and Tesco cat. number 100-5501.
I should mention that Tesco don't make these things themselves: production is contracted out and the results marketed under the Technika umbrella brand... this makes it potentially difficult to generalise comments about features to other models in the 'same' product line, though I've found similar in reviews of older players.
Whilst I don't have the manual I'm not exactly a lackwit when it comes to consumer electronics, plus the scant other reviews I can find of Technika players mention similar shortcomings to those I found... most notably that this player doesn't seem to allow you to change directories. This would be understandable on an old 128/256Mb player that only held a couple of albums, but is inexcusable on a 2Gb (1.88Gb formatted) model holding hundreds of MP3s. Not being able to navigate by folder reduces you to remembering what albums you have on the player or mainly using it in shuffle mode.
A partial solution if you have a selection of albums you like listening to as complete discs is to join the tracks together (i.e. have one MP3 per disc) with something like the freeware MP3 Album Maker.
EQ modes are available, which do predictably little. Sound quality is decent enough, but there seems to be a circuitry problem (probably not a one-off case as another reviewer also found this): burbling high-frequency feedback is at times apparent. This might not bother you for listening on the move — it doesn't get louder if the volume is turned up — but isn't something that should be present at all, and suggests particularly shoddy engineering. It isn't constant in volume, and manifests most when the player is reading a new track or receiving input from the controls... unfortunately, the times you're most likely to notice it.
Other negatives: despite the capacity, the fact Tesco are selling these in 2007 and USB2 being released as a standard in 2000, it very definitely isn't a USB2 device; it takes around an hour to fill. There's also no 'hold' switch, so if kept in a pocket the chances of knocking the joystick control mechanism to change volume or track are high. The current track is saved between sessions, but not your position within that track.
Plus points: configurable backlight, auto-power-off, the menu is accessible without stopping playback, WMA playback is handled, ID3 tags are read, there's a basic voice recorder mode, and no external cable is required to connect to a PC. Files are sorted by path rather than just filename, so sorting into directories does serve some purpose.
For someone who just wants a player to hang around their neck and take walking / running the Technika MP-407 isn't a bad buy at eight quid; for twenty it's unacceptably lacking in several areas. For those considering a different MP3 player from Tesco, its faults are possibly contained to this model, but try to remember to keep your receipt, eh? And for anyone considering buying store returns from eBay always verify you have autorun turned off for removable devices before sticking it into a PC, and virus-scan your purchase; this one, for instance, came with the previous owner's music and was infected with a trojan. Caveat emptor...