It's much faster. the ubuntu image that hardkernel builds boots to a full desktop in about 20 seconds.
Think of the rpi when it was first released. The drivers are still getting the bugs kinked out.
1- UHS mode doesn't work with most cards, and causes conflicts.
2- Ethernet. they are still working out the speed issues. Although it is sort of patched
3- USB has some dropouts.
4- They are still playing around with assigning irq interrupts to the various cores.
5- HDMI does not work well with some monitors, and non HDMI monitors don't work well at all. I don't have my monitor working with tinycore yet. I'm using the serial console to monitor the boot process, and then using ssh to connect headless.
But they are fixing and releasing binary updates daily, And the kernel is available via git.
If you have the Odroid Ubuntu image running, read the odroid wiki to build the kernel. You can build the kernel an modules in an hour. If you have not built an initrd for core yet, then you need on read up on that. This post is a nice summary. http://forum.tinycorelinux.net/index.php/topic,14634.msg88856.html#msg88856
After you build the initrd, you will also need to run mkimage to wrap the image for uboot.
mkimage -A arm -T ramdisk -C none -d initrd.gz initrd
The other trick to uboot is tell uboot to relocate the ramdisk to high memory, otherwise it gets overwritten but he kernel when it decompresses. Add
setenv initrd_high 0xffffffff
just before the bootm command. That step should not be necessary once we can remove enough modules from the initrd to get the ramdisk down in size.