The iPhone 5 finally hit store shelves Friday, after a record-setting pre-sale run of 2 million. At the end of the day, carriers are still tallying up their sales, but report that they had brisk sales days.

Sprint spokesman John Taylor said that the carrier is all but sold out of the iPhone 5 as of 5 p.m. Friday and is already taking names for the waitlist.

“At this time, the majority of Sprint-branded retail stores are seriously constrained or sold out of iPhone 5 inventory provided to us by Apple,” Taylor said. “Our stores will be resupplied as soon as additional devices are received from Apple.”

That’s bad news for the impatient. But chances are that if you’re in the market for a phone but didn’t hit the stores on the first day, you’ve got some questions about the phone.

To help you out, here are five things to know about the iPhone before you buy.

Speed demon: The new iPhone has a new chip, the A6, which makes the phone immediately, noticeably faster than its predecessor. Even when running on the same WiFi network, Web pages loaded seconds faster on the iPhone 5 than on the iPhone 4S. It’s also hard to find fault with the speed boost you get running searches on the 4G LTE network — that is, if you’re in a place that has LTE coverage.

The only app that really felt like it slumped for me was Maps — which you’ll see has its own problems, if you look at our coverage of iOS 6. Videos were clear and smooth, and even switching between apps felt snappier.

New materials: Get a clear case for this iPhone, if you can. It’s great-looking, though its taller, slimmed-down chassis may initially give you the feeling that you’re going to snap it right in half.

The aluminum and glass construction not only make the iPhone nice to look at, it gives it a feeling of quality that’s arguably missing from plastic-backed competitors such as the Samsung Galaxy S III.

Although the back of this phone may feel sturdier than the glass on the iPhone 4S, the aluminum will most likely be prone to scratches and wear. A case is still probably a good investment.

Bigger screen: One of the most noticeable changes to the phone is, of course, the fact that it’s longer. Apple’s kept the width of the iPhone the same but stretched it out about a quarter of an inch.

As a person with smaller hands, I’m a fan of the way Apple handled this size change. It’s not a strain on my thumb, and ends up giving you more screen to look at Web pages, books or videos. I’ve had to change my grip on the phone a bit to be able to hit the back button with my thumb, but not so much that I felt the phone was off-balance.

The screen was also great for looking at photos taken with the phone’s improved camera. And Apple did a good job when it came to handling how the phone works with apps designed for the previous screen size. Instead of stretching out older apps, Apple chose to bracket the top and bottom of the apps in black to keep things in proportion.

The cord: Much has been made about Apple’s decision to change the power cord on this phone, because so many people have accessories and cords that work across their iPhones, iPods and iPads. That is definitely a pain, as is the fact that you’ll have to buy a separate, $29 adapter to connect your old stuff. The change makes the phone smaller, but doesn’t appear to charge the device any faster.

There’s only one main advantage to the connector — it’s designed so that you can’t put it in upside-down.

Call quality: I wasn’t expecting to be making any comments about the call quality, but there is a noticeable difference when you actually use the iPhone as, well, a phone. The call speaker clarity is good, as are the microphones. That comes in handy when watching and recording video as well.

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