Your concerns are well-founded. I just got my Galaxy Nexus, and while it immediately made my Nexus One feel quite old, the size is really not comfortable. As far as I can tell, it's going to be impossible for me to fully operate the phone while maintaining a grip on it. Opening and closing the notification drawer, for instance, is impossible for me without shifting the phone or holding it in such a way that it's balanced on my fingers.

That said, two-handed operation feels great, and ICS is just wonderful. If I knew a phone with similar specs, an open bootloader, and a smaller screen was coming in the next two months, I would wait.