I was never an iPhone doubter, nor was I negative about the importance of the App Store and third party apps, but I have to admit how insanely wrong I was about how popular it would become. I was using my knowledge of past "catalog" apps, such as Brew's or Java stores, to color my predictions of the App Store and assumed moderate success and eventually some sort of black eye for Apple. Woops.
The way it's worked up until now is that mobile phone users would get a new phone from a carrier, explore all the cool bells and whistles and start downloading like crazy - for the first 2-4 weeks. They'd binge on ringtones, wallpapers, digital services and apps (mostly Java games). Then they'd get bored, or - more likely - get their first bill, and the downloads would drop off dramatically. I've seen charts and graphs to this effect, from both app developers and carriers.
Incidentally, I suspect this is why "subscription" apps became so popular - because they knew that users would sign up for a bunch of these types of apps, and long after the users had forgotten *where* the store catalog app was on their phone, they were still getting billed.
Anyways, this is what I thought would happen with the iPhone. I didn't really think about it, I just used 2-3 years of previous mobile phone catalogs as a basis and assumed it was some sort of ingrained phenomenon. Like Tom Peters says, it's hard to "unlearn". Instead what's happened is that iPhone users are insane downloaders of new apps. They fill up their 4 or 5 pages of icons as fast as they can, and seem to be constantly ready to download the newest or most trivial apps as they come out. (There definitely *is* a bump of activity after a new iPhone or iPod Touch is purchased, but instead of going away forever, it just tends to die down a bit instead.)
Now, whether the half-billion downloads number beats other app stores like Brew's or say Vodafone's Live download service, I don't know, but I don't really care. The fact that there's less than 20MM iPhones out there now, means that the average number of downloads per user is insanely high, and that's what makes it so interesting to me to observe.
So let me make some educated guesses why the iPhone App Store is seeing such massive usage, yeah, based on my own personal experience and observations. Not sure if any one of these things make the big difference, or if there's a combination of them all, but here's some thoughts.
* Third party iPhone Apps aren't segregated from the "core" apps when it comes to accessing them. If you want to make a phone call - a principle function of the device - you have to go into the "phone app" by clicking on it's icon, which you can place anywhere you want (though it's normally found in the bottom tray). This is quite different from other smart phones, where there is clear separation between what is integrated functionality, and what is an add-on. In my mind, this makes third party apps seem more integral to the iPhone user experience. (And, btw, is a serendipitous effect of Apple's reluctance to open up the platform in the first place, not part of some genius master plan).
* The iPhone builds on habits and functionality already ingrained in a generation of iPod users who are used to using the iTunes store to grab the latest and greatest hit song or album. Using the same exact process to download new applications makes it an evolutionary step for iPod users, and therefore cause less uncertainty for new buyers. I know people who are very conscious of their mobile phone bill and therefore won't try any sort of downloads for fear of being over-billed for the app or data or both.
* Millions of iTunes users credit cards are on file - a massive number that makes it easy for Apple to get into a new iPhone users's wallet right away without additional steps. Also, Apple has already set up a network of iTunes gift cards available at any grocery store, so even if you're a youngster with an iPod Touch and no credit card, you can *still* get access to apps by buying a iTunes credit, or getting one as a gift.
* Apps are also managed from the PC, again providing confidence to a user - both in terms of browsing for new apps, downloading them, managing them, updating them and backing them up. Also if you buy a new or additional iPhone, or buy an iPod Touch, you can share your apps among them. It's lots of little things like this which ease the "friction and fear" that normally accompany a consumer download.
* iPhone users are being shown how to use their devices for things other than just being a mobile phone. Lots of marketing dollars have been spent to show users cool things they can do with the iPhone out of the box, as well as new functionality that can be had from the App Store. The expandability of the device is sold as a primary feature unto itself (as any decent platform should be) therefore users will spend time browsing through the app store to find interesting things to download because, honestly, that's what they're supposed to do.
* There's tons of free apps, clearly marked as such. Unlike traditional carrier decks, where ridiculous 2Kb ringtones cost $4 apiece scaring users from downloading *anything*, on the iPhone there's tons of content where it's clear that it won't cost anything to download and try. Every iPhone also comes with a built-in data plan and WiFi, taking away worries that users will be charged obscene prices per kilobyte just for trying out a new game.
* The general iPhone app quality, it has to be said, is astounding. The only decent mobile apps you get from third parties on other phone platforms tend to be games from big players like EA, but even the smallest developers using the iPhone SDK have created some really insanely cool apps. This is in *addition* to the big players like EA, publishing stuff like Katamari Damacy and other games. You have to hand it to Apple for creating and providing such a great platform and development tools which has allowed developers to really go crazy.
So, taking all this into account, it's not really surprising that the download numbers are so high. Most are for free apps, downloaded easily, managed easily, found and used easily, updated easily, and the feature is promoted in prime time to millions of users on TV. I don't see commercials for download stores for any of the Verizon phones - just the phones or carrier itself.
Now, all this said... I've yet to see a "killer mobile app" beyond the integrated communication tools already provided in any phone, i.e. phone calls, sms, email, etc. So how important the iPhone's success in app downloads is an an example to other manufacturers (such as Nokia, my employer) I'm not sure.
Time will tell, I'm sure.