Woah, nice Mech. However, if I were making this machine, I'd made some parts differently. Like that:
Always think how this model would look and work in real. Spinning plate will not keep your arms in exact pose you want them to be. That's why I suggest to use 2x2 plate with one stud in center. It will ensure successful posing for arms.
I can't tell you want else I think you can fix to improve your model - I like to experiment with parts by myself, but I am pretty bad with constructive criticism. It's better to show redone version and compare it with original model. =)
But this is what I think:
1) You need to find an alternative to Orge hands, but not in complete parts.
2) Legs are a bit flat and not very good with posing IMHO so you should think this over and also try to add feet. =)
Anyway, the whole design of the model is awesome, especially torso and backpack! Keep up the good work!