I don't know about you but I always hated my ID photos when I had to seat still (like deadly serious/evil person, sometimes look like criminal lol). I have improved my "ID" look from smiling.
Tada--- my new one vs. old one. They are actually my favorites (because I put on lil smile so I can look more natural and less like criminal). The 2010 photo is already used for my passport (more than 6 months), therefore I have to take a new one for my visa, pretty happy with it even though I look more mature. By looking at the two photos, my neck looks longer and my face looks slimmer, and (lol) seems like I just got my nose done (just from the picture).