It is such a challenge because you have so many different factors to deal with. You have to consider the ambient lighting that you are doing the work in. Lighting effects how you see color, whether you are outdoors, indoors, have flourecents etc. You also have to consider that different people see color in different ways, so what may look good to your eye, may stand out like a sore thumb to someone else. The colors in the wood are also a factor. Wood is not a solid color, it has an 'overall color' but that is made up of under tones, highlights, wood grain etc. There can even be different colors just within the grain pattern! And finally, you have to consider the finish that has been applied previously. You don't know what the exact formula they used so you have to make judgement calls about how to mix finish to re-create that.
Add to all those challenges the fact that the wood grain runs two different directions. So now, on top of all your standard considerations, one side is going to have to have it's grain pattern painted on by hand. Regardless of all these challenges, the job came out beautifully. Looking at it now, unless you knew it had been broken before, you would never see the repair. And that is what we aim for, a repair you don't even know is there.