ok being BRUTALLY HONEST, this sounds like we're helping you out on a homework assaignment of some sort.

he looks too empty. I like the disjoin body parts, but there is just too much space. Either more body is needed or some form of connection like the suggestion above about glowing lights that might represent a magnetic connection.

He also reminds me a little bit of Vector Man for the Sega Genesis.

Ok, like many sayed it´s a good base but needs some extra...saz or something... here is what I came up with in two minutes... get some contrast in there.. I like red... the helm needs something two... red lazer in one eye seems ok... now since his limbs are dissconected anyway why not have some exra limbs... it worked for Dr. Ock and Goro so why not....

It instantly looked like a power ranger even before I read the comments.
Just changing the head isnt going to make it much less power ranger like in my opinion and the arms, legs, chest etc look far to generic of other super heroes.

Rayman Ranger.

Definitely looks like Vectorman.

 Continuing that line of thought, with extra limbs he could be given some alternate forms. He could have his current bipedal form, a tetrapod walking tank form with his legs changing into cannons, and a six legged insect form capable of crawling on walls and ceilings.

The floating balls between the body parts look like cop outs, there has got to be something better you can put there.
Also I would increase the size of the lower torso piece, make it more technical looking, that piece looks like it should be the 'core' of the guys body but currently it looks like a piece of old fashioned pottery. The upper body needs to have more of a 'back' from this perspective at least it looks like its cut off at an angle across his back and it just looks wierd.
Give him more sharp edges, a robotic hero needs to look high tech and metallic. That guy is so smooth he looks like he is made of cloth, especially his arms and legs. Also as everyone else has pointed out he needs a better colour scheme. Blue is a great colour for super heroes (Im guessing this guy isnt a villain? If he is change his colour, blue isnt very villainous XD) but it needs to be more varied, just chuck in little spots of other colours in there, personally I think some green would work great but hey thats up to you.

I spend way too much time on graphics boards, sorry for the long boring CC, =P.