After switching from an iPhone 4 about two weeks ago to a Galaxy Nexus with Android ICS 4.0.2 switched (with all the trimmings, the iPhone was at home with dead battery and without SIM card) and could initially also quite good friends with it, a forgetting the charging cable in the company has led to a nasty relapse. Because now the iPhone 4 came back and I have to say: although Android is the more open systems and the Galaxy Nexus is certainly a very good device, the form factor of the iPhone 4 remains more pleasant for me.
Also, with my personal usage patterns, I don't rely on being able to install a multitude of apps. On both iOS and Android, I only use a fraction of the options. I'm going to sell the Samsung Galaxy Nexus now, and at least for me, I know I can stick with my iPhone 4 without fear of missing out. And maybe the iPhone 5 will come someday, which could be a worthy successor to the iPhone 4 (with more changes than just better antennas and Siri ;)).