Lets start by saying that your work is technically sound, and you have all the basics sorted out. What follows is my personal opinion only, as all art is subjective take it as it is.
1. This model has already had so many paint jobs put up it really is hard for yours to jump out as anything different from this one picture, this is where you initially lose people, there is no WOW spot. The green try to be the wow spot, but it really isn't.
2. That leads us into focus points, while a near monochromatic paint scheme as this can be very eye catching, you haven't taken the highlights into the "pop" zone and so everything just kind of blurs together when you look at it.
3. The above 2 lead me into what I would say is the real reason this is the 6-7 range for me, some shading, nice highlights but nothing else added or unique to the model (freehand, unique color scheme, ect.) mean this is a nice table top quality and nothing more.
Hope this helps, if you want the magical 8 (for most of us) your really going to have to put allot more in.
