2. It's thin. The iPhone 4 is no chunker; it's about the same thickness as the new Droid Razr M, which Google is marketing for its thinness. The iPhone 5 has an obviously thinner profile. There's plenty of upside to thinness, as that'll make a big difference to how it feels in your pocket, and will give a little benefit to easy one-handed operation, too.
3. It looks like an iPhone. When the iPhone 4 came out, it was a striking departure from the 3GS before it. The iPhone 5 looks very much like an iPhone 4. Is this a bad thing? I don't know. The iMac has looked pretty much the same for the past five years or so, an no one has complained about that.
4. The difference in the screen isn't obvious. Until you hold an iPhone 4 or 4S right next to a 5, it's not obvious that the 5's screen is longer. The 44 percent increase in color saturation wasn't obvious to my eye either, but I didn't get a chance to take any pictures with the iPhone 5.
5. It weighs less. The iPhone 4 and 4S have a certain heft to them — I think the glass on the back might have something to do with it. Compared to Samsung's Galaxy SIII, you can definitely feel the difference.
With the iPhone 5, it feels like Apple's gone in another direction — they really focused on making it lighter. That should make it easier to hold for long periods of time, but it also feels less substantial.
Is the iPhone 5 likely to be a hit? I'd say yes, for a few reasons.
(Read more: Apple Introduces Thinner, More Colorful iPhone 5.)
One, the iPhone 4 and 4S were blockbuster hits in their own right, and the 5 isn't a big departure from them. If you were going to buy the 4S for $200, there's nothing about the 5 that's likely to turn you off.
Two, the fact that parts for the iPhone 5 started leaking online back in June suggests to me that Apple CEO Tim Cook decided to ramp up manufacturing for this phone pretty early.
The aggressive launch schedule for the phone — Apple is launching in nine countries next Friday and 22 more a week later — also suggests Apple has made tens of millions of the new iPhone and is ready to ship them around the globe.
That's particularly important during the holiday season, which is kind of a one-shot deal for a lot of consumers. They have money they're ready to spend during the gift-giving season, and if you have the product they want to buy on the shelf, you've got a deal. If not, they might not still want it in January. It looks to me like Apple is likely to satisfy a lot more of the demand in this crucial period than it has in the past.
(Read more: Reactions to Apple's iPhone 5— The Buzz on Twitter.)
Three, momentum. I've seen a few pundits complaining about the iPhone 5 design, and the fact that it's not a major departure from the past two years' worth of iPhones. From an investor perspective, the lack of change is only a problem if Apple is failing to respond to an important market trend.
The iPhone 5 has LTE, a larger screen, and improved camera features — those could go a long way toward helping it stack up well vs. phones like the Galaxy SIII or the Droid Razr Maxx.
At this point, Apple's bigger challenge is making enough phones and sending them to places where people want them — it's not getting people to want a new iPhone. Everything about yesterday's launch presentation suggests Apple is on track to do even better than it has in the past.