About me: I am currently using an iPhone 4S 64gb. With all the apps and music I keep on hand I only have about 9gb available. For this reason, I'm doomed to buy another 64gb iPhone. What I hate about iPhones is how it's almost required that you update OS in order to get newer games and the OS itself almost cripples the device you once had working flawlessly.
The 1520 will accept a 64gb memory card, so free space shouldn't be a concern. In addition, set up skydrive, and you don't need to store more things locally.
I use my iPhone constantly. Since I take a train to work, I game the entire time. Sometimes it's simple stuff like Words With Friends or JetPack Joyride. Sometimes I like some of the higher end FPS games that Gameloft produces. My current hook is Dead Trigger 2.
Look through the wp app store to see if you'll be satisfied with the games out there. Most other apps seem to be available for wp, but games don't really seem to make their way over as often. This may be a big issue for you if you like to game on your phone a lot. You may be better off with a large screen android device, like the Note 3, if you're unhappy with the game selection for wp.
I'm also a photographer with a high end Nikon DSLR. Obviously you can see why a 1020 or 1520 would peak my interests, especially with some very finite manual controls over ISO, Exposure and WB (I do wish aperture was controllable).
If you like to use your phone camera a lot and are a pro, there's a compelling reason to look into the 1020 (the camera).
I keep a comprehensive collection of my photos on my iPhone and often use it to show perspective clients my work. I post all my work online but it's always watermarked. In fact, the ONLY time you'll ever see my photos without a watermark is if I'm sitting with you and allow you to scroll though them on my iPhone. It would be nice to show that work off on a bigger screen.
tablets have bigger screens than phones.. but if you want to use your phone for that, well, the 1520's screen is gorgeous. 6in and higher dpi than the tiny iphone screen. i think you'd be hard pressed to find anybody, whether or not they like wp, who would say negative things about the 1520's display.
1 - If (God forbid) I lose my iPhone with all those full resolution, non-watermarked photos, I'm not overly concerned with someone retrieving them. Not saying it's impossible but the majority of people that find the phone would probably not be able to retrieve any files from it. As compared with an Android or Windows phone with a MicroSD card in it. Pretty much anyone that finds one of those phones can pull the MicroSD card and retrieve any files from it. (Somewhat related, I see posts about the 16gb vs the 32gb 1520..... what's the difference if you're just going to cram a 64gb MicroSD in it anyways?)
there are ways to encrypt a sd card, but as i've said, you do not need to even bother with that. buy the space you need on skydrive and set your phone and computer to sync with it. when you pull up your camera roll, everything on skydrive is there complete with thumbnails. with how well skydrive integrates, you don't really need to store anything other than apps locally.
2 ? Security. Obviously concern ?1? is security related, but overall security is a big deal to me. In the world of personal and business computers, Apple has always been (or at least perceived to be) the more secure OS. Less vulnerabilities and attacks than a Windows platform. Is the same true in the smartphone world?
from what i've read about the way wp works, it's inherently going to be more secure. apps cannot see data from any other apps. every app thinks its the only app on your phone, and ms very strictly controls what apps are allowed to access and do.
3 ? Apps. As I mentioned, I love my games. I have a friend that made the switch from iPhone to a Samsung Galaxy S4 (at the time it was the flagship of any Android). After a week he went back to iPhone. He claimed that in many cases they had the same app but it was usually an older version than what he had on his iPhone. And that's in an Android market which has significantly more apps than W8 does. Are we seeing true development in apps in general in W8?
development has sped up a lot and the wp store is now pretty decent, but it's still not even close to on par with the itunes app store, and it won't be for the foreseeable future. here, judge for yourself, you can fully view the app store from here:
The Smartphone Reinvented Around You | Windows Phone (United States)
just one thing to note that does annoy me a little. while the wp apps tend to be much nicer looking than their ios/android counterparts, they also tend to lack features, as if the developers half as$ed it. for example, the wp tapatalk app looks great, but it lacks multiquote, and lacks moderation functions. the wp kindle app (which i note is not one of the better looking apps anyway) won't let you view kindle magazines or documents, only kindle books. the amazon store app doesn't allow in-app purchase of kindle books and you need to go to the amazon web page (which it will conveniently link you to) for that title to buy the kindle book you wanted.
4 ? Picture quality. One thing I noticed with the 8mp camera on my iPhone (which does take fantastic photos for a camera phone in my opinion) is that no matter what settings I use, the end result is still just a 72dpi photo. I'm just not sure what good it is having a 41mp or 20mp camera on a smartphone if at the end of the day I'm getting a low resolution 72dpi photo. Are any of you noticing this when transferring to a PC? I called Nokia support to pick their brain but they had me on hold for over 30 minutes and then said they'd get back to me although I'm not hopeful they will (which would make them on par with Apple and the horrible support they have).
the 1020 and 1520 can store the original full resolution raw files. given how high the mp count on both are, especially the 1520, when you set the pic sizes to normal and not to huge blown up 72dpi versions, you'll have a very high dpi count.
5 ? Continued support. Since MS has purchased the Nokia phone division, is there a future in owning a Lumia right now? Obviously in two years or so I'll probably end up with something else but I'd at least like to know that for the next two years I'm not on an abandoned platform.
MS didn't buy them to stop them from making phones. they may be rebranded (or maybe not), but the same people will be making the phones, and lumia's will continue to be supported.
I apologize if I rambled but this is a pretty big commitment. I'll be saddled with my decision for the next two years.
if it makes you feel better, if you look around, you can get either a 1020 or 1520 for dirt cheap on contract. i think i've seen the 1020 for practically free on some deals. this would at least free up a little money for you to buy another phone if you decide wp isn't for you.
i'll give you my overall take on WP as an android user who recently made the switch. i wouldn't say WP is "better"... it's different. in fact, it's so different that it's almost like MS set out to make a mobile os that had nothing at all in common with android or ios. it's easy to use, and has some superior features, but also has some inferior features (no separate volume for ringer and music? really? no forward button in IE? come on now). some standout features i would point out would be outlook (imo by far the best mobile email app out there), skydrive, and office (mainly because it integrates to well with skydrive; there are plenty of good office clones in the google play store). the nokia apps are all well done, and you're not really missing anything by going from google maps for your maps/nav to the nokia options.
i see some odd things posted in here, like wp being more "personal" than other os's. maybe than ios because ios doesn't let you change anything, but android? eh, you have far more freedom to customize android than you do wp. i see excuses for the wp app store (which really needs no excuses anymore, other than in the games area) such as "wp is social centric not app centric" which is silly given that often apps are needed to access social media. wouldn't put too much stock in that stuff being true. although on the topic of wp being "personal", if you're coming from ios, wp will definitely feel more personal, as you do have a lot more freedom to configure stuff than you do with ios.
good luck with whatever your decision is. btw, info on the upcoming iphone 6 has been released, and there will be two versions. a 4.8in screen version and a 5.5in screen version, so more screen real estate will very definitely be an option for you if you choose to stick with ios.