I already mentioned most of these things on Face book to you, but i will reiterate them here. All these points are from personal opinion and some experience with 2 android phones, Motorola xoom, galaxy tab 10.1, the Ipad 1 and 2, the Iphone 3gs(my current phone for 2.5 years) and the Iphone 4.
Iphone 4s
Pros for The Iphone 4s:
Camera:
The new camera that has been implemented on the Iphone 4s looks to be quite a pro to me. The new optic design, iris, and light sensor looks to have drastically improved both colour quality, lighting, and clarity. The photo clarity I doubt is rivalled by the S2 but I have not used this phone or seen pictures taken by it so I cannot say for sure. The 1080p video with real time stabilization seems to make quite a difference for when you want to pull out your phone and take a quick video of something. No more shaky cam crap. I doubt the 1080p will be any better than the S2 (if it does indeed record in 1090p 30fps) but considering the video stabilization I would give the Iphone 4s the edge in this department.
Geo Tagging:
I love this new feature. I honestly have no idea if there is a way to do it on android but i think its pretty cool, and personally for me it would be super useful.
Music:
I highly prefer the iPod/iTunes interfaces over androids music listening experience. It has everything you need in a very simplistic arrangement, and podcasts are right there on iTunes for you. I have not used many third party apps on android though, so if anyone has experience that trumps what I just said with an app that makes it better, let me know. But to be honest, the iPod/iTunes combination is pretty great. Everything you could possibly want, music, movies, tv shows, and podcasts are pretty readily available for you on an Iphone.
Screen:
The retina display has quite awesome pixel density per inch. I really liked that about the iphone 4 (that's about all i liked though
)
Apps:
You have 35 dollars worth of apps for IOS already. The Apple App store is also a very matured app store. In my opinion the Apple app store has a larger number of superior apps in both quality and function.
Call quality:
Theoretically speaking the Iphone 4s should have great call quality with its antenna design, no better or worse than the s2, but not as crappy as the Ip4
Siri: I know that you said you would never use it, but it still is a pro that the S2 does not have. Siri is like speech recognition software on a computer, the more you use it, the better it can do what you say. Who knows, you may try it out and love it. Then you can go walking around town talking to your phone.
Cons for the Iphone 4s:
Screen:
The Colour reproduction on the Iphone 4s I would wager is less than the Sup Amo screen on the S2
Front Facing Camera:
The front facing camera on the iphone 4s like the iphone 4 is still only vga quality.
Customization:
Practically no customization, and contrary to apples beliefs, changing the background is not a feat of customization.
Battery:
The Battery life is less than that of the S2 by what I have seen and read online, but how that translates into real world battery life is an entirely different story, one that I cannot comment on because I has to do with how you use your phone and how and when you charge it. According to online articles, the S2 has better battery life in both 3g, browsing, and standby time.
Texting:
The screen is not as good for txting. Again I have never used the S2 but i have used other android phones with similar screens and they seemed much easier to txt on, and less incorrectly hit letters occurred.
Design:
The iphone 4 has a thin, sleek, strong design, but the glass is sort of annoying, and if you drop that one too many times on a bad angle that is going to crack.
Samsung Galaxy S 2
Pros For the GSII:
Screen:
The screen on the S2 is larger, this might be better, or worse for you. Personally I find the iphone to be just about the right size for my pocket, anything bigger would be too big for me. Given the S2 has a bigger screen I'm guessing it has larger dimensions to match it. The super Amoled screen that the S2 features has better colour reproduction like I said earlier as well.
Music:
Supports flac, which for me is not really a need, because I don't really have that large of a flac library, but if you do then that is a big pro.
Customization:
Android is much more customizable then IOS. Including the fact that you can have widgets. Personally I dislike widgets. I find it no easier to use a widget then go into an application. So this is no pro for me at all, but it might be for you. (keep in mind you can get widgets on the iphone using cydia, I have never attempted this however, and it does void your warranty to jail break your iphone)
Front Facing Camera:
The front facing camera on the S2 unlike the iphone 4 and 4s is 2mp, instead of vga, sure not much of a difference when it comes right down to it, but it is still a slight advantage.
Ram: The S2 has more ram. How well the phone is optimized to use this ram however is the difference from this being a pro or not. Seeing as i don't have experience with either of these phones to compare them, im going to make the assumption that the S2 will get a tad bit of an advantage from the extra ram.
Flash:
Supports flash
Cons for the GSII:
I have most likely mentioned all these cons above but I will reiterate them again here.
Screen:
Has less pixel density. (con could be the larger screen size as well, that's is completely your personal preference however)
Apps:
The android market place is less matured, and in my opinion does not have the number of quality apps that the apple app store. I don't have a vast amount of experience with the android market place however, so someone like mac would be able to comment on this better.
Design:
The larger screen size makes the overall phone larger as well. This is a con for me, and I'm pretty sure it is for you as well by what you have told me in the past.
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All these pros and cons for each device are pretty even, they are both great phones. It all comes down to your weighting system on the pros of each device. For instance if flac audio and a front facing camera quality are big concerns for you then the S2 is the way to go. If rear camera, and the Apple app store are your wants, then the iphone 4s is where it at.
This spew was not very well thought out but i hope i brought up some thoughts for people to think about, and gave you some information to make your decision.