I think camo is fine on marines so long as it is not overdone (after all I have my marines done in camo as well :D). My suggestions to you are:
1) pick a different base colour. The grey looks too much like straight plastic with some white/black dots thrown on.
2) pick out the trim in a slightly different colour. This will help separate the areas of the marine and define the detail a bit more.
3) the green guns do not go with the camo colours you have picked out. I would suggest a gunmetal look or a flat black instead.
4) less is more. When doing camo colours, there is no need to go crazy and 'cover' the model in them. Just a bit here and there will help to break up the natural lines of the body and looks far more effective, paint theme-wise, than having too much.
For a reference, here is one of my marine squads in a camo pattern. Note that even though the armour is a rusty red, the trim is done in brass. While the brass blends a bit with the armour, it also picks out the separate areas of the armour. Also, note how I picked out the black camo sections with a light gray colour. This is a further tip to help define and make the camo and paint stand out a bit more.
Don't get me wrong I am not trying to hack on you or your minis at all (that ripper kicker is awesome btw), I am just presenting an alternate and just as effective way to do camo to you