If you were taking a college course called iPhone 101, your professor might identify three factors that have made Apple’s smartphone a mega-success.

First, design. A single company, known for its obsession over details, produces both the hardware and the software. The result is a single, coherently designed whole.

Second, superior components. As the world’s largest tech company, Apple can call the shots with its part suppliers. It can often incorporate new technologies — scratch-resistant Gorilla glass, say, or the supersharp Retina screen — before its rivals can.

Third, compatibility. The iPhone’s ubiquity has led to a universe of accessories that fit it. Walk into a hotel room, and there’s probably an iPhone connector built into the alarm clock.

If you had to write a term paper for this course, you might open with this argument: that in creating the new iPhone 5 ($200 with contract), Apple strengthened its first two advantages — but handed its rivals the third one on a silver platter.

Let’s start with design. The new phone, in all black or white, is beautiful. Especially the black one, whose gleaming, black-on-black, glass-and-aluminum body carries the design cues of a Stealth bomber. The rumors ran rampant that the iPhone 5 would have a larger screen. Would it be huge, like many Android phones? Those giant screens are thudding slabs in your pocket, but they’re fantastic for maps, books, Web sites, photos and movies.

As it turns out, the new iPhone’s updated footprint (handprint?) is nothing like the Imax size of its rivals. It’s the same 2.3 inches wide, but its screen has grown taller by half an inch — 176 very tiny pixels.

It’s a nice but not life-changing change. You gain an extra row of icons on the Home screen, more messages in e-mail lists, wider keyboard keys in landscape mode and a more expansive view of all the other built-in apps. (Non-Apple apps can be written to exploit the bigger screen. Until then, they sit in the center of the larger screen, flanked by unnoticeable slim black bars.)

At 0.3 inch, the phone is thinner than before, startlingly so — the thinnest in the world, Apple says. It’s also lighter, just under four ounces; it disappears completely in your pocket. This iPhone is so light, tall and flat, it’s well on its way to becoming a bookmark.

Second advantage: components. There’s no breakthrough feature this time, no Retina screen or Siri. (Thought recognition will have to wait for the iPhone 13.)

Even so, nearly every feature has been upgraded, with a focus on what counts: screen, sound, camera, speed.

The iPhone 5 is now a 4G LTE phone, meaning that in certain lucky cities, you get wicked-fast Internet connections. (Verizon has by far the most LTE cities, with AT&T a distant second and Sprint at the rear. Here’s a cool coverage comparison map: j.mp/V5wEwN.)

The phone itself runs faster, too. Its new processor runs twice as fast, says Apple. Few people complained about the old phone’s speed, but this one certainly zips.

The screen now has better color reproduction. The front-facing camera captures high-definition video now (720p). The battery offers the same talk time as before (eight hours), but adds two more hours of Web browsing (eight hours), even on LTE networks. In practical terms, you encounter fewer days when the battery dies by dinnertime — a frequent occurrence with 4G phones.

The camera is among the best ever put into a phone. Its lowlight shots blow away the same efforts from an iPhone 4S. Its shot-to-shot times have been improved by 40 percent. And you can take stills even while recording video (1080p hi-def, of course).

So far, so good. But now, the third point, about universal compatibility.

These days, that decade-old iPhone/iPad/iPod charging connector is everywhere: cars, clocks, speakers, docks, even medical devices. But the new iPhone won’t fit any of them.

Apple calls its replacement the Lightning connector. It’s much sturdier than the old jack, and much smaller — 0.31 inch wide instead of 0.83. And there’s no right side up — you can insert it either way. It clicks satisfyingly into place, yet you can remove it easily. It’s the very model of a modern major connector.

Well, great. But it doesn’t fit any existing accessories, docks or chargers. Apple sells an adapter plugfor $30 (or $40 with an eight-inch cable “tail”). If you have a few accessories, you could easily pay $150 in adapters for a $200 phone. That’s not just a slap in the face to loyal customers — it’s a jab in the eye.

Even with the adapter, not all accessories work with the Lightning, and not all the features of the old connector are available; for example, you can’t send the iPhone’s video out to a TV cable.

Apple says that a change was inevitable — that old connector, after 10 years, desperately needed an update. Still, Apple has just given away one of its greatest competitive advantages.

The phone comes with new software, iOS 6, bristling with large and small improvements — and it’s a free download that also runs on the iPhone 3GS, iPhone 4 or iPhone 4S.

The chief attractions of iOS 6 are a completely new GPS/maps app (Apple ditched Google Maps and wrote its own app); new talents for Siri, the voice-activated assistant (she now answers questions about current movies, sports and restaurants); and one-tap canned responses to incoming calls (like “I’m driving — call you later”).

There’s a new panorama mode for the camera, too, that comes in handy more often than you might expect. As you swing the phone around you, it stitches many shots together into a seamless, ultra-wide-angle, 28-megapixel photo. Unlike other apps and phones with panorama modes, this one is fully automated and offers a preview of the panorama that materializes as you’re taking it. (For mycomplete review of iOS 6, see nytimes.com/pogue.)

Should you get the new iPhone, when the best Windows Phone and Android phones offer similarly impressive speed, beauty and features?

The iPhone 5 does nothing to change the pros and cons in that discussion. Windows Phones offer brilliant design, but lag badly in apps and accessories.

Android phones shine in choice: you can get a huge screen, for example, a memory-card slot or N.F.C. chips (near-field communication — you can exchange files with other N.F.C. phones, or buy things in certain stores, with a tap). But Android is, on the whole, buggier, more chaotic and more fragmented — you can’t always upgrade your phone’s software when there’s a new version.

IPhones don’t offer as much choice or customization. But they’re more polished and consistently designed, with a heavily regulated but better stocked app catalog. They offer Siri voice control and the best music/movie/TV store, and the phone’s size and weight have boiled away to almost nothing.

If you have an iPhone 4S, getting an iPhone 5 would mean breaking your two-year carrier contract and paying a painful penalty; maybe not worth it for the 5’s collection of nips and tucks. But if you’ve had the discipline to sit out a couple of iPhone generations — wow, are you in for a treat.

It’s just too bad about that connector change. Doesn’t Apple worry about losing customer loyalty and sales?

Actually, Apple has a long history of killing off technologies, inconveniently and expensively, that the public had come to love — even those that Apple had originally developed and promoted. Somehow, life goes on, and Apple gets even bigger.

So if you wanted to conclude your term paper by projecting the new connector’s impact on the iPhone’s popularity, you’d be smart to write, “very little (sigh).” When you really think about it, we’ve all taken this class before.

E-mail: pogue@nytimes.com