My friend Peter Cohen penned a well-thought out essay outlining his reasons for not upgrading to an iPhone 3GS. Since I made the same decision when the iPhone 3G came out last year, I thought it would be good to take a look at why I found the 3GS a compelling upgrade this year.

I bought the original iPhone as week after it was first introduced in 2007. (Yes, I paid $600 for it back then and no, I did not feel “cheated” when Apple dropped the price a few months later.)

I instantly fell in love with my iPhone. I use it dozens of times a day and count it as the most useful device I own. For me, the iPhone has become a powerful enough tool that I’ve stopped taking my laptop with me on short business trips and I rarely take my MacBook Pro out of its bag when I fly. Watching an in-flight movie on my phone is a perfectly pleasant experience -- much more so than trying to find a good angle where I can keep my laptop open enough to see its screen.

Still, when the 3G was introduced last year, I had no trouble deciding not to upgrade. For me, the improvements on the new phone simply weren't compelling enough. Essentially, the iPhone 3G added just a few new features: GPS and of course, access to AT&T’s faster 3G network. Otherwise, the specs were identical to the new phone: no faster processor, no internal architecture improvements, no extra RAM. GPS was tempting, but with a unit already in my car and a handheld unit for camping and hiking, it was a “nice-to-have” and not a “must-have” upgrade. In my area of the country, 3G coverage was still spotty at best, so that didn’t seem worth the cost of the new phone. And when you factored in the $10 a month increase in the price of the phone’s data plan, the math got pretty easy: I’d pass on this one. In fact, one of the improvements I was most excited about was the switch to standard-recessed headphone jacks: not exactly a reason to drop an extra couple hundred bucks down on a phone.

This year, though, a lot has changed. For one, AT&T’s 3G coverage is much more pervasive now -- pretty much saturating both the areas where I live and work. My handheld GPS unit had given up the ghost, too—so I’ve been considering a new one.

But the real temptation came in the hardware improvements on the 3GS. I love the idea of having a video camera with me all the time, and now I don’t have to buy a separate device to accomplish that—sorry, Flip Mino. The improvements to the still camera are pretty compelling too: adjustable focus, macro capability—all very cool. Now, throw in 32GB of storage space (four times what I had on my original iPhone!) and perhaps most importantly of all, the faster processor, double the RAM and all the other internal improvements. For me, those performance improvements are a game-changer almost on the level of the original iPhone. Most of the time, using the 3GS on a cellular network feels as fast as using it on WiFi. It’s an improvement I was not fully prepared to experience and I still find it stunning.

As one who’s been there, I can certainly empathize with those 3G owners who can’t justify moving up to the 3GS after just one year. I will say, though, that I’ve never been happier to have skipped an upgrade. With the enjoyment I’m getting out of my 3GS, just call me a charter member of the “Every Other Year iPhone Club.”