I have one,
Got it not long after release.
The new firmware improved the issues people were complaining about, but to be honest i never had those issues anyway!
I have since bought a magic memory card adapter and jailbroken it with the latest hacked firmware, and its pretty much a dingoo now, as it has many emulators and roms installed.
I remeber reading that tommo did actually pretty much completely rip off dingux OS from the dingoo for this, and the emulator it uses for the NeoGeo is not actually as good as the dingoo one.
Its not a bad toy for playing NeoGeo games, and they are fairly faithful in the emulator, and compared to some of the other emulations handhelds, it does have a bit more of a quality feel, but the joystick that comes with it feels like it came out of a cereal packet compared to my real NeoGeo stick!
I sometimes take it away with me on he train etc, but mostly it gathers dust in my front room, i'm still of the opinion that still nothing can hold a torch to emulation on the old sony psp2000.