The lack of Find my iPhone and other useful first-party apps on Android
As a former iOS user, I can say that nearly everything from the usability and customization part of my iPhone 4 has drastically changed with my embracement of Android 4.2 on my new Nexus 4. Everything.. seems so fast, fluid, and I can do so many more things with my phone, including having Google Now tell me how long it will take me to go home from a new destination or the satisfaction of paying with my phone at a local coffe shop daily. It's just that Android is missing something when it wants to attract the average iOS user to its platform.
Those things are little things such as Find my iPhone or iCloud backup that are available out of the box when someone purchases an iPhone, iPad, or iPod touch. I know that you will probably say "install Find my Droid, Cerberus, PhoneLocator Pro, etc." or "use Titanium Backup." The simple truth is that everyday consumers do not do this, because they have no idea that Google platform doesn't offer these things. An example is my friend, who owned a Galaxy S III, of which realized that someone had stolen her purse. She contacted the authorities and then me and I said to her, well if you installed a free tracking software such as Lookout, you may have actually been able to track your device and other belongings, given that the thief was not that intelligent.
My theory is that that Google does have the opportunity to lure more customers from iOS to its Android platform, given that iOS is fairly weak right now, with many customers currently leaving (including myself). Samsung has obviously advertised a lot, which explains their booming sales, and as announcements of future products such as the Galaxy S IV, which is coming very soon.
Come on Google, fix these minor issues and you will make myself and many others very happy :)