While the motherboard had worked well with Ubuntu Linux, the integrated GMA X4500 graphics was the troubling spot. With the driver that ships with Ubuntu 8.10 we experienced extremely slow performance and other problems while with the latest driver and using all of the latest bits (including GEM), we could not even start the X Server. In a few months time though much of the invasive Intel graphics work should hopefully be over and the stability regained.
Aside from the integrated graphics problems on Linux, the ASRock G43Twins-FullHD was a fine motherboard. This motherboard provides both DDR2 and DDR3 memory support to allow for a gradual and easy upgrade process, has integrated Gigabit Ethernet, supports all of the modern Intel LGA-775 CPUs, and has six Serial ATA 2.0 ports. At a price of under $90 USD, the ASRock G43Twins-FullHD is also a very affordable motherboard.
If you are looking at the ASRock G43Twins-FullHD or other G43 motherboards and intend to use Linux, you may want to use it in conjunction with a discrete graphics card until the recent Intel driver work has settled. If you don't intend to use the integrated graphics, you have nothing to worry about and this is a very affordable motherboard that worked "out of the box" with Ubuntu 8.10.