I just returned my Galaxy Nexus and am back on the iPhone 4 after using the Galaxy Nexus for a week. I loved the phone, but it has some major issues, for me, that made it a downgrade from the iPhone 4.
I do not consider myself an Apple fanboy even though I have used an iPhone since the launch of the first iPhone in 2007 and have used Macs since 1995. However, I do consider myself a perfectionist, and things that other people don't even notice drive me bonkers. I have tried almost every Android phone that has been released for the last two years, and the reason I keep trying Android phones is because I'm sick of the iOS UI and I want a larger screen. Ice Cream Sandwich has a beautiful UI, and I greatly prefer it over iOS. I hope that Apple makes some drastic changes to the iOS UI in the next update to make it again feel exciting to me. Otherwise, I will likely move away from iPhone permanently in the future if they don't change the UI and use a larger screen.
The Galaxy Nexus has a beautiful screen. However, the Galaxy Nexus screen is Super AMOLED and not Super AMOLED Plus, which means it is using Pentile instead of RGB like newer devices, including the Galaxy S2, are. This makes the screen not quite as sharp as the iPhone, even though it is a higher resolution and very close to the same PPI. Also, blacks were amazing, but whites were not. Next to a phone with an LCD screen, whites looked very dingy. However, the screen complaints weren't deciding factors in my decision to keep the phone or not to.
Like I said, I am a perfectionist, but it wasn't those imperfections in the screen that killed the deal for me with the Galaxy Nexus. I had decided to accept those things because I love the UI of ICS, the inky blacks, and large screen. But when it comes down to the most important features of the phone, the phone just sucks. For me, the most important things are battery life, camera quality, call quality, signal strength, and music streaming over bluetooth.
As a multimedia device, the Galaxy Nexus is amazing. The inky blacks and vibrant colors means you can watch movies and look at pictures and be amazed every single time. However, just the screen being on drains the battery at half a percent a minute, and doing anything at all drains the battery at one percent a minute. I'm not exaggerating: I left the screen on and watched the rate at which the battery drained. In my week of use, I was fully draining the phone and recharging it every day, and a couple days I actually fully drained it again after recharging and still was almost dead before the end of the day after the second charge. For a device that is used on the go, I can't rely on it if it dies that quickly. I'm not always in a position that I can recharge it as soon as it dies, and I'm not going to start carrying an extra battery with me.
Another thing that is high on my list is camera quality. The camera in the Galaxy Nexus sucks. As far as that goes, every Samsung Galaxy device I've tried had a horrible camera. Every picture even if taken in great lighting looks like it has been ran through Photoshop's watercolor filter. Every picture looks smudged and has no fine details. Low-light pictures which the device is actually advertised as having "top notch low-light performance" are terrible. They seem to have tuned it to snap photos faster at the expense of quality.
Regardless of all of the features a phone has, it is still a phone and making calls is kind of a big part of the package. The Galaxy Nexus has bad signal strength and horrible call quality. My mom has an iPhone 4 on Verizon, and in places where she had one or two bars, I had none, and I would be unable to get an internet connection while hers would load web pages just fine. And even in places where I had all bars, the call quality was still horrible. On top of that, bluetooth call quality was also horrible both on my end and the receivers end. I make calls from my car over bluetooth every day, and it is unacceptable to me to not be able to understand what is being said because of the crackling I hear over bluetooth. With my iPhone 4, calls have always been crystal clear over bluetooth.
I also listen to music over bluetooth in my car every day during my one-hour-each-way commute to school, so that is also something important to me. The implementation of AVRCP is screwed up in ICS. When playing music over bluetooth, connected devices won't pause the music. It will stop it but it won't pause it. When I receive a call, every other phone I've had, including phones with previous versions of Android, would pause the song and resume it upon ending the call. Not so in ICS. It stops playing music and upon ending a call it replays the song from the beginning. Multiple calls during a single song could mean not being able to get through a particular song for a while. Besides that, ICS still only supports AVRCP 1.0, which means no metadata over bluetooth. iOS, Windows Mango, and WebOS all have AVRCP 1.3, which is important to me since without it it just says "streaming" on the screen in my car instead of displaying the song title and the artist name.
Yes, the Galaxy Nexus is unquestionably a better multimedia device than the iPhone, but it sucks as a phone, it sucks as a streaming music player, and it sucks as a camera, when compared to the iPhone 4S. What works for me may not work for you, but for me the Galaxy Nexus is not a replacement for an iPhone 4. It is a terrific replacement for an iPod Touch, though, but as a device that is used to make calls and that is used outside of the house and away from a power source, it just isn't reliable.