I have a special reason to seek this insight: I did nearly the same thing, and my app makes THREE figures per YEAR. I read this post hoping to gain some insights as to why. I was disappointed.
Actually, I didn't do what he did. If I did what he did, I would be making all that money. My complaint about the post is that it didn't help me discern the key differences.
In March 2010 I introduced Bill It [1], a time tracking app. I was motivated by my own need combined with a desire to get into the exciting world of mobile apps. Like the author, I was a .NET developer by day. As a contractor I wanted something for myself, and I figured I was not unique.
I want to be very clear that I am not surprised of my lackluster results or jealous of his success. (Well maybe a bit jealous.) I approached it as a build-it-and-maybe-someone-will-come-but-who-cares-because-its-fun-and-I-learned-something kind of thing. It hurts my head a little to think about it marketing, so I built it and threw it out there.
But so did he: "Surprised to see it getting some traction, I decided I should take HoursTracker a bit more seriously."
His app took off with no marketing at all. Mine did not. Had I been able to say this about Bill It, my whole story would have played differently. Had I seen the proverbial fishing pole starting to bend, I would have grabbed it and stared reeling, as he did. Is that a post hoc rationalization? Maybe, but I don't think so.
So what made the difference? Time-to-market? Features? Try-ability? Pricing?
TIME-TO-MARKET
As others have said, time-to-market is important because the app store keeps the winners at the top, and it's easier to get to the top early on. Maybe I was just too late to have a chance without serious marketing. Who knows?
FEATURES
My "killer feature" was supposed to be Quickbooks Integration. I was running my consulting business on Quickbooks, and I needed to get my hours input in order for billing to be linked to payments, deposits, revenue, etc. I created a very nice feature set to accomplish quite smoothly (if I say so myself). I decided not to add a timer. I explain the rationale in the product description. Perhaps this was a bad decision. Who knows?
TRY-ABILITY
Bill It launched shortly before in-app purchases were introduced. So I created a "lite" version and a full version. As soon as in-app purchases came out, I added a "full" purchase in the lite app. Did I "accidentally give too much away for free?" No. If anything, I erred on the opposite side. The Quickbooks integration took some setup work, so my main goal for the lite version was to allow the user to verify it before paying. I only allowed 5 time entries, which was plenty to see how the app works but not enough to actually use it. Maybe that was the problem. Who knows?
PRICING
Just before Bill It came out, another time tracker featuring Quickbooks integration came out. Although I thought my integration feature was superior, their app seemed to have a few more features and a little more polish, so I tracked just below their price, ending up at $8.99 (about the same as the pro version of HoursTracker), which is still a high price as apps go. Maybe a different pricing strategy would have been better. Who knows?
I want to clarify another point. I don't expect the author the know what made him successful where I and others weren't. My real complaint is that the rest of us expect that of him. From the first word of his title, "How," we can see that he wants to meet this unrealistic expectation. The post would have been better titled "HoursTracker earns five figures a month on the App Store" but then no one would read it I guess. I told you, I'm bad at marketing.
[1] https://itunes.apple.com/us/app/bill-it-lite/id367603023