Personally, I would use Photoshop or Corel to add a lens flare over the lamp. If this is one frame from an animation, this can be tedious, but the effect is quite good. Alternatively, check out some of the tutorials on this site. At least one of them deals with lighting effects, like halos around flames and simulated lens effects. In my experience image realism stems primarily from well built models, thoughtful camera placement, photo-realistic textures (materials), and lighting. The way materials deal with light is of tantamount importance. For example, at first glance it appears that the material used to render the ground, or street, is more affected by the lamp than the walls. Since both materials are basically the same (simulated stone or brick) they should probably be more similar in this respect. I would fiddle a bit with the ambient & diffuse setting on these materials, and ensure they match each other.
