I'm sticking up for Sheva all over this site! >=o
Now she is nominated for being the worst sidekick?! WHAT?! A good 90-something percent of those who've played RE5 and complained about Sheva's AI probably never used the Cover/Attack commands, which do in fact change her battle tactics and the weapons she uses. Also, you can get a trophy for building a strong bond - you do so by pressing circle (command button) in the right timing: complementing her headshots and team combo involvement; thanking her for supplies, healing and resuscitating; giving her equipment in game (i.e. weapons, ammo, herbs, etc...); responding to her requests promptly (i.e. ammo or help); healing her and resuscitating. The stronger a bond with your partner, the stronger her/his AI.