I have no idea what you guys are talking about. I've had ZERO issues with data on this phone--well, aside from the nationwide data outage we've been seeing.
Camera: This is the best camera I've seen on an Android phone yet. My D1 was pretty crappy, but worked. The D3 camera was pretty similar in quality to the D1. I have Camera Zoom FX, FxCamera and HDR Camera installed, but the stock camera app is sufficient for 90% of my photos. Would you believe that his picture was taken with my GNex?
3G: My D1/D3 had spotty 3G coverage in my office building (8-story tower). I switched to the GNex and I now get full 3G in my office, whereas I was lucky to get 1-bar before.
4G: The only place I can't get 4G is in my office--which is to be expected. If I go to the break room in the corner of the building, I get instant 4G and speeds of up to 20 Mbps. Hell, most of the time I leave WiFi off, as 4G is just as fast for me.
Battery: So far, the battery life on this phone is CONSIDERABLY better than that of my D3. I had to (reluctantly) use Juice Defender to get a full days use out of my D3. Do you know how much it sucked to have to wait 5+ seconds for data to be reenabled after unlocking the device and launching an app? SOOOO painful! I leave my GNex on my desk at work all day long, and frequently use it for different tasks (chrome-to-phone, barcode scanner, etc) and the battery life is sufficient for my needs.
Responsiveness: I thought the D3 was a huge jump from the OG Droid, even if my D1 was running CM7 at the time of upgrade. However, the jump to the GNex was just...incredible. I hopped on my wife's D3 the other day to check something, and it was almost painful to use.
Build quality: I will admit that the build does feel a bit...cheaply-built. The D1 and D3 had a nice solid body, and the metal bezel around the screen approved the overall look and feel. The volume button on the GNex rattles slightly, which isn't really an issue, but is just somewhat annoying. The biggest issue for me, though, was how wide and thin the phone was. I like my phones naked, but I have to use the silicone case on this phone, or I feel like I'm going to drop it. Both my D1 and D3 had battle-scars on the screen bezel from hitting the pavement, and I'd like to avoid that with this phone, thankyouverymuch.
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TL;DR: You seem to be experiencing issues that most users aren't. That seems to be an issue with that specific device, not all of them as a whole.