When I first got this player I was amazed at how good the sound quality was, it truly is one of if not the best DAP's out there in terms of sq. However there isn't much to say about the Teclast T51 other then sound quality, because other then that this player is utter garbage. The user interface is dreadful, it has a mere 8 hours of battery life, adding files to the system is horrendously slow and updating the firmware is a nightmare. When uploading files to the main memory of the unit, I average about 3 mbps which is absurdly slow, and reading files from micro SDHC cards can take forever. Also the system lags constantly and while your waiting for it to load if you accidentally hit part of the screen it will automatically register the input and apply it once its loaded. And if you have lots of folders like I do this can get very frustrating as you accidentally click the wrong one because it lags, then you have to start from scratch and the beginning of all the folders as theres no way to go back to previous folders. The screen also is very scratch prone it would seem, the very first day I got this palyer I accidentally dropped it and bang a huge scratch across the screen. I've also tried updating the firmware on this player, and after some research it appears the only way to really do so is whilst connected to a computer running windows xp which unfortunately I don't have access to.  I do have to compliment the Teclast T51 for its great screen quality though and the amount of different video files it supports, I think the screen looks better then my iPod touch(provided it didn't have the scratch that is). And the ability to expand the memory with a micro SDHC card is nice as well. Overall I'd say for it's price this DAP is a bargain for an audiophile thats only interested in sound quality, however if your interested in anything other then sound quality in your DAP this is certainly not the DAP for you!