Why is Instagram so popular?

Update: Literally minutes after this post went live, Facebook announced that it was buying Instagram. My post still stays. I am not surpised but curious to know why Facebook agreed to pay so much for an app (ok, a mobile photo sharing network). I could see Facebook integrating Instagram into its photo sharing feature. The convergence is obvious. Just not sure about the price. Then again, Facebook's cash+stock purchase makes sense given Facebook's valuation. Maybe they are not spending just as much as we think.Lets get the obvious out of the way. I am not sold on the incredible popularity of Instagram. Not saying it is bad. On the contrary, it is a pretty nice app or a mobile social network if you want to call it that. But I just dont get why it is so popular. Let me explain.When the app first came out in Oct 2010 on iOS, I had an iPhone 3GS. Soon everyone with an iPhone was talking about or sharing Instagram pictures on Facebook and Twitter. The first few pictures were fantastic. The filters rocked and gave a whole new dimension to the photos. I made a mental note to download it on my iPhone and get on the Instagram bandwagon. Work and life ensured that I never got around to doing it. Something curious then happened. I started getting bored and soon, really tired of watching the same old filters and the same old Instagram. In fact I started observing a trend where good pictures were losing their charm thanks to the photographers obession with instagramming it. The originality and color of pictures were being taken away by a set of filters. It is not much a fault of the app as much as people wanting to Instagram every picture.I was apparently in the minority. Instagram grew bigger by the day until it hit 30 million users recently. That is a remarkable achievement. And all of this on just iOS. At this point, it was ready to make its move to Android. Last week, Instagram launched on Android to great fanfare and huge reception. I figured why not give it one more shot. I diligently downloaded the app, signed up for an account and then took a picture to tweak with Instagram's filters. I then went to my goto app for photography tweaks- Pixlromatic and realized that I had far more options and far cooler effects than Instagram. And there are many more on Android that offer way cooler effects for 99c to 2.99. Why then was it so popular?Coinciding with the launch of Instagram on Android, I had started observing tweets from iOS users complaining about Instagram being available for Android. It made no sense. Wouldn't it be cooler for the app and more importantly the network to span multiple mobile OS's. More the merrier, I say. But the sense of elitism that iOS felt with the availability of Instagram exclusively to them was now gone. And trivially so, people felt that it was no longer cooler.So was it the iOS exclusivity that made Instagram cool in the first place or was it the wow factor?. Or was it just media hype with every tech blogger using it?. Was it the allure of a mobile social network or was it a mix of all of the above?. I have no idea. To me, it is just another app. Definitely polished and well done. But nothing extra special warranting all this attention. And all good apps have good alternatives these days. No exception to the rule. No exception for Instagram too.