Portraits are more technique than camera.
Any camera is good for portraits but I would recommend a longer focal length if possible. The 55mm end of the 18-55mm kit lens is acceptable but I get better portraits on my D5000 with the 70-300mm lens.
A longer focal length will give faces better proportions (no hidden ears or big noses), make it easier to declutter the composition, and reduce the depth of field so you can have a completely blurred background.