Aside from the orange making the green look like some etheral puked all over it, I really can't put my finger on exactly what I don't like about this paintjob. I think that it's the freehand bits, especially the "lightning" inside the blue space of the generator, your freehanding looks blocky and not blended, and it seems to be with most of your green/orange Tau pics. If the freehand was used much more sparingly, or blended much better, than I could even get past your color scheme (which aethstetically, makes feel a bit like throwing up). I will go on to say though that your pics suggest that you have grasped the many complex ideas and techniques floating around on CMON, and you've absolutely got potential to be awesome, I suppose it's just gonna take time and practice.