Ok, my friend, here comes the hammer. I'm like this on bakuc, they cant take it, if your here, you can, and are going to take it.
First issue, I know what you wre trying to do with the scratches, but remember your scale. Some of the places it couldnt get scratched like that, without causing other damage as well. If it smacked into rocks there would be dents and dings as well as scratches. http://codyscoop.com/ht-building.html check that for more info.
The decals on the shoulders are done well, and from what I can see about the paint chipping on the edges looks good.
Black is VERY hard to do, especially for large scale like this, you have to be VERY careful with it. I really dont recomend it (I did a kit with that exact same scheme, except gold instead of gray)
http://www.bakuc.com/modeler/smeagolthevile/1580 I used to be happy with it... not so much now. atleast, with the paint. Im happy with my mods, wish I had it to do again so I could get it better.
Lastly, the hammer.
SEAMS!!!!
Gundam kits arent like tanks or planes where seams can be tollerated if there on the right spots. ALL seams need to be removed. inner and outer parts of the shoulders, the whole rifle. Front and back of the thighs.
Seams are the one thing that every gunpla modeler should beable to do better then any tread head, or flyboy. Its going to take ALOT of work to make them all disapear, but you HAVE TO, if you want anyone to take your gundam builds seriously.
There is a wave of idea going around that you can leave the seams and they are still good builds, to this, I direct people to 'Anti-art' http://en.wikipedia.org/wiki/Anti_art. If you want your gundam kits taken seriously, you have to fix the seams. If your not going to, why not just snap it and play with it, because at that point its still a toy.