The speakers aren't great but that seems to be par for the course. With headphones, it's pretty decent. The mp3 player has several EQ presets, but no manual one that I have noticed so far.
I need more TV testing, but that's what I seem to use it for the most often. The games look good, better than on the screen, I think. I've had a problem with one encode, having the a/v synch fall apart, but that seems to be related to an individual encode, not a blanket problem. (And I didn't do the encodes so I have no idea what the encoder did. It could be a corrupted file for all I know, though it plays fine on my computer.)
I've been having problems with the SD card, but I seem to be the only one so I'm still open to the possibility that it's the card itself. I have yet to get another card to test with. (And I have nothing else that uses micro SD.)
As for two player... it works. I even figured out how to load different games with the controllers plugged in, which up until now was thought to be a bug, but it actually just moved to an undocumented button combo.
Mine likes to freeze up on me, though. I haven't seen anyone else have this problem so maybe mine is just defective. So far the SD card acting up has done it, and also plugging it into a wall charger with the game turned on usually freezes the machine.
And by freezing I mean I need to take the battery out to turn it off.
So... it's not perfect, but having a small, portable handheld/media player which doubles as a digital VCR (minus recording) and Game Console all in one... it's pretty neat. The combination of the 2-player option and the TV option is what sold it for me, even though there's more powerful handhelds available.
Looking forward to some more firmware upgrades... I haven't tried GBA games in it yet but I know the button mapping is still messed up for them.