You have got multiple problem with your model.
- Your Character's head has half an extra meshes with the mirror modifier.
I select the extra vertices and deleted them.
- You have overlapping faces on within the model.
I removed the extra faces with W key, then select "remove double"
- The body of your character have normals facing in the opposite direction.
I corrected the the normals with CtrlN.
Here is the blend file after I corrected those issues. The weights are now correctly applied.
I must say I have noticed that your have rigged the hand IK object to the hand bone. Shouldn't it be on the lower arm bone, you might have to get a better tutorial on the subject. Your bone objects are not rotated to the correct front facing position at rest. Always check your bone orientation with it's local axis turned on.
Here is the improved rig.