To start with it includes a number of in depth painting tutorials for 13 models. Within those there are some discussions about individual techniques and concepts. The range of models is good ranging across WFB, 40K and LotR.
A nice feature is that at the end of most of the articles there are a selection of other 'Eavy Metal models that illustrate the technique that the tutorial focused on. In this case OSL from the vermin lord.
Finally there are some very nice discussions about particular techniques which talk about the theory, where to find inspiration and how to achieve various concepts. This is a photo of the NMM page.
12 of the 13 tutorials have been printed in White Dwarf but unless you have the correct issues this is the only way I know of getting these.
It's not cheap, but probably cheaper than sourcing all 12 WDs and you get the 13th tutorial and the extra bits as well.
The paints are the old citadel versions but this isn't too much of an issue if you have the conversion chart or you are happy judging it yourself.
So in conclusion I think it is a great resource if you want to try to improve your painting but not worth it if you already have the relevant WDs.
What have other people found useful when improving their painting? Can you recommend any literature?
Please feel free to leave any comments, tips or questions below.