Having said that, I do agree with you on the GNexus screen size. 4.65" seems a little over the top..
I do know a few people who prefer smaller screens, but it does seem that 4" is around the sweet spot for most people.
Unfortunately not for everyone when using "auto brightness".
I haven't laid hands on a Nexus yet, but I'm speaking from experience with my digital camera (not quite professional quality, but maybe one step down - still a very good camera). It has a similar mode (ISO-3200), which takes pictures instantaneously (no lag). The quality is dramatically lower with this mode, though, even though the camera takes beautiful pictures otherwise. I can speculate as to what causes this at the hardware level - it's not hard to imagine - but I'm not well-versed enough in digital photography to explain it.
What I'm curious to know before buying a Nexus is whether this can be turned off, or if it's built into the hardware. If the former, then flashing a custom ROM (or even a different camera application) could solve the problems.
I think that tradeoff with the zero-shutter-lag feature is that the phone does a cursory attempt at focus/metering/white-balance (if it does one at all) and totally misses it most of the time.
You can try to focus by tapping the screen first, but it still doesn't quite get it right in my experience.
The camera quality is really bad. When using the flash indoors, the colors seem to be off by a mile. You can turn off the flash but then images are (obviously) dark and blurry. It's disappointing because things like the zero-shutter-lag and panorama features should make this an awesome camera phone, but it seems like they skimped on the camera hardware. Or maybe I just have a bum unit and I should make a warranty claim?
My other issue is the size. It seems that every flagship device (that is, one with specs worth buying at all) on the Android platform is engaged in this arms race for bigger and bigger screens. Frankly I think the old Nexus One and the iPhone are the perfect size.
Apple seems to have no problem selling 3.5" screen phones like hotcakes, so I don't know why the Android manufacturers think that the only way to sell phones is to have giant devices.