It is one of a selection of "colourised" photos in an article on War History Online. Whilst I don't think it is necessary for photos to be in colour to be interesting, there is clearly something about this extremely well "coloured" black and white photo. The article details the work the likes of Doug Banks and Royston Leonard are doing, and I must confess I found it fascinating.
There is also a Facebook page, WW1 Colourised Photos that feature many more, not always as good, but often of interesting subjects, not just the Western Front. If you have any interest in WW1 it is well worth checking out.