I traded my Nexus for a 4S and here are my thoughts on it, and the things I miss and don't miss:
Things I miss about the Nexus -
I miss 4G (sometimes when 3G is lagging, it's not an everyday thing), I miss the big screen for watching videos and surfing the web, I miss the customization. Customization and widgets are my biggest gripe. I really miss not being able to make my phone mine. I also miss having app settings in the app.
Things I don't miss about the Nexus -
The mic cutting out, the screeching sound in your ears during calls, the occasional random reboot or frozen phone, the screen banding in lower level brightness, and the multitouch issue during certain games.
Things I like about the 4S -
I like the smaller form factor most of the time. I will never never never use a belt clip. It won't happen. And sometimes the Nexus was a little uncomfortable in pants pockets. The smaller 4S is a little less noticeable. I like the notification lock screen. I also really like how everything looks the same, notifications and apps. This is kind of a double edged sword. I miss the customization on the Nexus, but at the same time, my OCD sometimes didn't like how everything looked different. But I still miss the ability to do some of the customization. I like the music integration. This is a great music playing device, and that's important to me.
I kinda covered what I don't like about the 4S in my ramblings. But for me, it does work a little better. I always had the feeling that the Nexus wouldn't work when I needed it. Whether this was justified or not, I don't know. But it does have its issues. If these get fixed, I'd probably go back. But for right now I need the more reliable phone. This is in no way meant to flame the Nexus. I do love the phone. But I wanted to give some insight on what I thought. I think they're the best two phones on the market, and I wouldn't blame you for using either one.
Hope this ramble helped a little. And I'd be happy to answer some more questions about my switch.