I recently picked up one of these sweet little boards, and I have to say I'm pretty pleased. It is a stripped down version of the Odroid C1+, designed to be lighter, and more configurable to suit your end purpose.
It is based on a quad core Amlogic S805 running at 1.5 GHz. It sports 1GB of RAM and both micro SD and emmc slots for storage. Oh, and did I mention it only costs $25. I have to give credit to the folks at ameridroid. I ordered this on a Wednesday night, and it was in my mailbox the following Friday, for ~$5 shipping.
Here it is compared to the Original Odroid C1:
As you can see it is quite a bit smaller than the C1 and it comes with most of the connectors unpopulated. The only installed connectors are HDMI, RTC battery, and LiPo connection. It also has an on/off switch.
The board does include the charging circuit for the LiPo battery. There is a connector pack available which contains the necessary connectors to fully populate the board. One improvement over the original C1 and what brings it closer to the C1+ is the addition of the I2S connector for high quality digital audio output. The connector pack contains the 40 pin GPIO header, the 7 pin I2S header, the serial connector, the IR receiver, and both a single and double USB connector that you can populate to suit your needs. The connector pack is available for an additional $2.95 and is well worth it. You can even choose to have Ameridroid install some or all of the components for a small fee, some as low as 40 cents.
The board boasts a reduction in weight from 40g to 16g, and a 24% reduction in overall board size.
The 40 pin GPIO connector pretty much matches up with the Raspberry Pi's connector, with the exception of the built in ADC pins. One of the ADC in pins is connected to the LiPo battery circuit to allow monitoring of the battery's capacity. The 7 pin I2S header matches up with the Odroid HiFi Shield, which features a TI (formerly Burr Brown) PCM 5102 DAC.
In addition the GPIO connector provides:
2 - I2C Ports
19 GPIO Pins
2 ADC inputs
1.8V Analog reference
3.3 V Out
2 5V outputs
1 SPI Output
The things that they removed from the board were the Gbit ethernet port, 2 USB ports, leaving 2 on board, and the USB OTG port.
I will have to say though, I'm not a big fan of their choice of power connector, the 2.5 mm barrel jack is not the easiest in the world to find, and when I first powered this board up I found I did not have a solid power connection and suffered from continuous reboots, but once I figured out the issue it has been rock solid ever since.
On my board the first connector I chose to populate was the serial console port, this allowed me to monitor the device on first boot and do some initial configuration. The second connector I chose to populate was the dual USB connector. With this in place I was able to connect a USB keyboard, mouse, and a Edimax WiFi adapter. Once all these things were installed I was able to boot up, connect to my network, update the OS and get started on my journey.
All in all I have to say I'm pretty happy with the board, bear in mind with it's light weight, reduced connectivity, and ability to be powered via LiPo battery, it's probably more targeted to be part of a specialized embedded solution that doesn't require networking, or as a wearable of some sort. I would expect, since it uses the same OS images as the C1 and C1+ that the expectation would be that prototyping your solution would be done on one of those devices then the resultant SD card could be placed in the C0 for deployment.
As this is pretty much a scaled down version of the C1+, most of the information in ODroid - Oh Boy! is directly relevant to this board, with the exception of the addition of the I2S connector, and the fact that the HDMI connector has been changed to the Type A standard full size connector.