With multitouch gestures and swype, my faith in smartphones is restored. I'll probably going to try one.
Tiny physical keyboards are out, so it's really iOS (iphone) vs Android. I'm sorry to say that Apple is going in the way of the PC market. Android has taken over, huge, but Apple will remain profitable, trend setter, and cute.
The first thing to look at is the screen resolution, not the size. iPhone 4 and 4S has 960x640 pixels. At 326 ppi (pixels/inch), Apple call it retina display. If you are old enough, it should look like those light boxes for viewing films for slides. Anyway, you should not be able to see pixels.
But density and resolution isn't that crucial. It's image problem, yours. You may not want to see all of a web page in a 3+ inch screen. At that super density, it will be sharp but there's other coloring and lighting problems. I won't and can't go into that but really it's your image problem.
iPhone 3 is worthless at 1/4 of the resolution and about 1/4 of the density. There are plenty of Android devices at the same resolution and size - even cheaper.
There is the new Android phone, Galaxy Nexus, that has HD display 1280x720p. The screen is slightly larger at 4+", but that's pretty standard in Android phones. There are the odd one or two Android phones with screens slightly denser than the iPhone 4, but they don't really sell, and hard to find.
The most common Android phone has screen resolution 800x480, about 4"+. It doesn't look that much compared to iPhone 4. But imagine that the best netbook, like the MacAir, with it's screen height squeezed into less than 4 inches. You need good justification to have a higher ppi screen, other than my phone is sharper and smaller than yours.
The screen has something to do with playing back HD videos. Piping out the data via the Himi connection to the TV is easy. Decoding, resizing and filtering to display on a smaller phone screen takes more processing power. So expect jitters if you don't have HD screen, and a powerful processor.
Next criteria - carrier and network.
You still want a phone right? In US, the network is still split between AT&T and Verizon/Sprint, the same old GSM vs CDMA network. Now that GSM becomes WCDMA/3G/UMTS, it would be rather confusing.
You can't go wrong with AT&T and it's resellers. Phones will be compatible worldwide, and most phones are quad band, not limited to USA or rest of the world. Either you have to get an expansive, unlock phone without contract, or you unlock the phone yourselves if possible. In past experience, you can unlock your phone via your carrier after a few months, saying that you need to travel.
Carriers find three different ways to charge you - voice, text, and data. It is ridiculous as not so long ago, text is only popular in countries such as Czech, for younger people to save money on phone bills. Now text cost more than voice, and voice is worthless. You can have free text, via data, but you need a smartphone with apps to go with it. Another justification for a smart phone.
Data speed is a major differentiator for networks. Verizon/Sprint got there first and call it 4G. The similar thing in AT&T is HSDPA for the rest of the world. These are normally included other than the most basic data package. However, unless you have a lot to upload and download in a rush, like HD video, 3G speed are decent.
High data speed is particularly relevant to WiFi tethering, where you use your phone as a WiFi router like you do at home, so all your WiFi capable devices can access the internet via your phone, anywhere where there is reception. All smartphones have WiFi and most are tethering capable, thought some cheap carrier resellers hide it. But the problem is that carriers charge an arm and a leg for it.
So I don't think data speed is relevant to average smartphone users. 3G speed is decent. Download videos you made via the SD card. And go to McDonalds if your computer need free WiFi.
iOS 5 vs Android 2.3
iOS is on the iphone 4S, not the 4, unless you hack it. Latest Android on phones is 2.3, mostly come with 2.2. Android 4 is only available on the latest Galaxy Nexus. Android 4 unifies the tablet version with the smartphone version of Androids.
The killer app for iOS 5 is Siri, the voice assistance that allows you to do very sophisticated things, according to Apple. Actually if you hack it, you can get it on iphone 4 too, and it's available to any OS soon, provided Apple don't crack down on it as in WiFi tethering. I think for average smartphones, most will be satisfied with voice to text, saving you a lot of typing.
Android has multitouch, while still hidden in iOS 5. I won't buy a smartphone without multitouch, the same that I won't get a portable without it. Considering it's cheaper than apple, it's a no brainer.
Many Android has swype out of the box, or you can install it yourself free. iPhone has it on app stores, but not as smooth and integrated. There are similar things on the Android market place with varying degree of intelligence. You can touch type without lifting your finger, by just sliding your finger on screen.
Android has better integration with Facebook, Twitter, and of course Google everything, if you like that sort of things.
Cam and Video
This are unrelated to playback on the screen. Later phones has HD video capture at 720p. The resolution is still less than 1 megapixels. At CAM mode the resolution is usually a bit higher like 3mp to 7mp. It's all about the len. There's no point to use the phone as a SLR camera. For HD video capture, it's worthwhile to get a cheap and small camcorder so you don't lost your expensive phone easily.
Most phones come with a decent len at the back, and many with an additional pinhole cam at the front for video conferencing, suitable on the go, with sufficient burring to compensate for the lack of makeup.
AT&T has the fashion accessory plan for the iPhone 4S, if you use the phone as fashion accessory only. It's $40 plus mandatory $15 data plan for the 4S. Text extra, if you don't know how to text via data. With this plan, you can't do much for the data, and hence you can't be smart much.
In contrast, it's reseller, Simple Mobile, has the $40 unlimited everything plan, up to 3G speed, upgradeable to 4G. It's BYO, bring your own phone. For iPhone 4S without contract, it can be just under $700!
Sprint reseller Virgin, has the $35 for unlimited data (4G?). It's Android lineup is pretty update and cheap too. But it's only for US and then some.
To maintain your international geek image without paying an arm and a leg, I recommend to get an Android direct from China, plus a Simple mobile plan.
Almost of the phones are made in China anyway. It's sort of open source hardware plus open source software Android. The display and chips are fairly standard. The best ones, 800x480, are over $200. It's International and 4G.
If you don't want that state of the art, $100 gets you a pretty smartphone and pretty display too.
Online marketplace sites like dhgate are ebay killers. There are numerous scan artists like eBay in the beginning but there are good protections in place. For standard electronics, you can get full refund if they don't ship you the numerous functions on the list.
Unlike eBay, they allows review too but people are't that talkative as in Amazon. Don't like the idea that the Chinese mafia has your name and card number in their record?
Anyway, there are plenty of reliable merchants and the units they sold worldwide is staggering.
Other reasons you need a smartphone
GPS - smartphones use network information, internet, wi-fi, in additional to satellites to provide accurate information fast. Some have turn to turn instructions and for me, a google map anywhere in the world is super for me.
Free text, free phone call via internet. But you pay the data package. A device good for HD porn will do your stuff justice.
Show your merchandise and portfolio any time. I still remember a non-story about a traveling sale person showing his next seat passenger in his brief case, electrical extension sockets with extension wire. Is that really still necessary?
A pair for grandma's and grand kids? It's so easy and so cheap with video, apart from the plans.