This is the perfect thread for me. I recently left my carrier where I had an iPhone 4 and was interested in the Galaxy Nexus. I purchased the GSM version, here in Canada, and gave it a shot. Here is what I found.
Galaxy Nexus:
I found the screen, especially at low brightness to have almost a film grain effect, especially when scrolling slowing in the web browser. The other problem with AMOLED in my opinion is that the colours are less realistic. I found the screen to almost have a blueish hue the entire time, throwing off the whites unless the brightness was turned up significantly.
The battery life is not perfect, leaving the screen at 25% brightness and taking it through a day, by the time I got home around 6 or 7 pm I had 30-40%. Not terrible for using it during the day. It mostly consisted of light web browsing, texting, and watching videos on the train. Had I used it heavily I doubt it would have given me a few days but I never tested that.
To be honest, the weight was a little lighter than I prefer. I am unsure if this was because I was use to the weight of the iPhone 4 or if it was really just to light. I felt a lot that I was going to drop it. I watch videos all the time going to and from work and I felt the device was difficult to hold in the landscape position without shifting your fingers. This causes a problem because the power button is on the side. It's the thing I hate most. I hold my device on the side a lot and all I ever do is hit that while I am watching a movie.
The speaker, well nothing good can be said here. That thing is as quiet as it gets. I had to use headphones almost all of the time to hear anything. It's a tiny speaker and if you plan to watch anything on it without headphones that speaker will not be suffice for anything. Even during general speakerphone calls I could barely hear the person on the other end. It's awful, no way around it.
Speaking about size and the back cover, the size is at first big. Over time you will get use to it and it will be easier to use. Even when I began to like the size, I still could not use one hand to reach the top without feeling like I was going to drop it onto the sidewalk. The back cover does have a nice texture though, but I hate how it peels off. It feels cheap and looks even cheaper. Doesn't at all make you feel like your holding a $700 phone.
The camera is abysmal. Every shot was grainy and didn't look very good. It was just awful. The software bundled with it for instant shots and editing is fantastic and beats IOS by far. I wish they would bring it over to the iPhone.
The app store is pretty good. Android has a large variety of apps, but IMO they are sub par. If you have never experienced the IOS App store I can see how this would look good but coming the other way it was nothing but disappointment. Some of the apps are the same on both marketplaces but androids almost always are ad supported and do not include all of the features that IOS does. Take for example fruit ninja. IOS has had a ton of updates for this game with new blades and the addition of extra levels and so on. Fruit Ninja on android is basically how it looked when it originally came out. Angry birds has Ads with no option to buy an non ad version. That is what really bothered me the most. I don't mind apps being available but at least have a version where I can pay to have a clean game. On the plus side google makes it very easy to see what anything costs and one click payment is a breeze.
ICS software is greatly improved from previous versions of android. It is a light year ahead of gingerbread and is going to be great when Google puts more work into it. My biggest problem with it is that while it looks much nicer it feels half finished. Like it's just lacking. It's really hard to put into words why it feels that way but take it home for a week and you can see. I had a few problems with applications crashing, including the internet browser multiple times and a few apps. I can't say this has never happened on my iPhone so it happens to everybody. It is a vast improvement and everyone should try it.
After about a week I very much missed the simplicity of IOS and left android and purchased a 4S instead. There is just something about IOS that without words makes it better than Android IMO. I think that the main selling point of Android is that you can customize it, and after I set it up the first day to the way I wanted I never changed it for the next six days and never felt the need to. I used the app drawer for getting to my apps, and my home screen just had a weather widget and my calendar. I think subconsciously I was looking for that IOS app interface and that is why I used the app drawer. I find things in IOS easier to get to, in some areas and harder in others. As far as the Galaxy line, I think whatever Google puts out next could really be something but they need to control the overflow of Android devices.
I have another opinion about Android and the "war" with IOS. Samsung has made the last two iterations of the Nexus line. I don't think they have put their full hearts into it. I think they put out a nice phone but reserve the best for their own lines of phones, Galaxy S lines. I think this is a major stumbling point for Google because their heart isn't really into it. Apple on the other hand has Samsung make specific parts and then makes sure what they put out is perfect in their eyes. I think Samsung really wants to beat IOS but wants to do so with their own line of products and not something that people associate with Google more so than Samsung. Most people say the Google Nexus or Galaxy Nexus but rarely is it referred to as Samsung Galaxy Nexus in common practice. Just my opinion but just wanted to see if anyone else agreed.
If you want to go Android definitely stay with the Nexus line but as far as 4S vs Nexus I would throw it to the 4S. I will stick with mine for the future and into whatever Apple brings out next.
P.S- Sorry for the wall of text.