Apple's two new phones, the iPhone 5s and the iPhone 5c, don't hit store shelves until this Friday, Sept. 20. But reviews for the 5s flagship are already beginning to trickle in. Here, a quick primer of what the tech world's top tech critics are saying about it:

David Pogue at the New York Times enthusiastically endorsed the new fingerprint reader that's built into the Home button.

The best part is that it actually works — every single time, in my tests. It's nothing like the balky, infuriating fingerprint-reader efforts of earlier cellphones. It's genuinely awesome; the haters can go jump off a pier.

The 5s can also scan your fingerprint when you're buying books, music, apps and videos from Apple, saving you the password entry (although this, too, is buggy; Apple says a fix is due on Friday).

You can teach your iPhone 5s to recognize up to five fingerprints — all yours, yours and your spouse's, or whatever. Apple says your fingerprint is stored only on your phone, encrypted and never transmitted or stored online. And using the fingerprint reader is optional; you can always use a regular password instead. [New York Times]

Darrell Etherington at TechCrunch said at first glance, the phone looks a lot like its predecessors. On closer inspection, however, the colorways are noticeably different.

The iPhone 5s inherits the design legacy of the iPhone 5, which means aluminum, chamfered edges and glass. But unlike with previous "s" class updates like the 4S, Apple has gone further, updating the look of the phone as well as its internals. For the silver model, that just means an updated home button to house the new fingerprint scanner, but there's an all-new gold finish, and a "space gray" version to replace the black model of the iPhone 5s.

It's hard not to wax too poetic about the iPhone 5s design; the color-matched conductive ring around the home button/fingerprint sensor adds a lot to the overall good looks of the device, and the new space gray finish that I reviewed is more visually striking than the black it replaces. It also seems more resistant to wear, as the iPhone 5 in black scratched when I even thought about it encountering some grit, while the 5s finish remains impeccable after a week of use. [TechCrunch]

Engadget's Myriam Joire said the new "big pixel" camera is a fine iterative improvement, but it isn't best in class.

First, let's tackle the camera's low-light performance. The shots we took with the 5s were consistently better than what we took with the 5: they were sharper, with finer details, more natural colors and far less noise. As you might expect, our daylight shots were roughly on par, though there were a few times when the 5s won out by a slight margin, offering just a little more detail. All told, the 5s plays in the same league as all those other flagships with a bigger emphasis on imaging. Even so, our sample shots still showed more noise and less detail than the same images taken with the Nokia Lumia 1020. The 5s also does a good job of reproducing color, but it's not the best performer in this category, either. Make no mistake, though: The iPhone has been — and continues to be — great as a simple grab-and-go camera. It may not be a best-in-class performer, but the vast majority of iPhone users will still be happy. [Engadget]

Walt Mossberg at AllThingsD said iOS 7 is "a shock at first," but still considers it "a step forward, despite a few issues."

There are too many new features in iOS 7 to list here, but it’s a big improvement. The icons have been redesigned to be flatter and simpler, but they appear to float over your wallpaper, giving the effect of depth. Many elements are translucent, subtly changing shades to match the wallpaper color.

The fonts are sharper, finer and more delicate. Buttons and controls are thinner and lighter and, in the browser, they disappear or shrink to make a little more room for content. Overall, the effect is to make the 4-inch screen seem larger. [AllThingsD]

AnandTech's Anand Lal Shimpi would still like a slightly larger screen.

The 5s builds upon the same chassis as the iPhone 5 and with that comes a number of tradeoffs. I still love the chassis, design and build quality — I just wish it had a larger display. While I don't believe the world needs to embrace 6-inch displays, I do feel there is room for another sweet spot above 4-inches. For me personally, Motorola has come the closest with the Moto X and I would love to see what Apple does with a larger chassis. The iPhone has always been a remarkably power efficient platform, a larger chassis wouldn't only give it a bigger, more usable screen but also a much larger battery to boot. [AnandTech]

Yet the A7 processor might be one of the iPhone 5s's more underrated improvements.

The A7 SoC is seriously impressive… As long as I was on a good internet connection, web pages just appeared after resolving DNS. The A7's GPU performance is also insanely good — more than enough for anything you could possibly throw at the iPhone 5s today, and fast enough to help keep this device feeling quick for a while. [AnandTech]


The Times' Pogue:

Apple still believes in superb design and tremendous polish. The iPhone is no longer the only smartphone that will keep you delighted for the length of your two-year contract — but it's still among the few that will. [New York Times]

TechCrunch's Etherington:

With the iPhone 5s, Apple once again wins the right to claim the title of best smartphone available... And thanks to the 64-bit A7 processor, this phone, more than any iPhone before it, is likely to be the device that grows more appealing as the software ecosystem catches up, which is great news for buyers looking for something that isn't so easily replaced by the next big thing that comes along. [TechCrunch]

Engadget's Joire:

The 5s is a solid effort from Apple, but its true worth is yet to be determined. If developers come up with clever ways to take advantage of the M7 coprocessor and the 64-bit support in iOS 7, the 5s will truly shine. If not, many people might just wait it out another year. [Engadget]

AllThingsD's Mossberg:

My biggest disappointment is that there have been only minor improvements to the keyboard. Unlike in Android, Apple still bars you from substituting third-party keyboards with better auto-correction. The company says this is due to security worries. Overall, however, the new iPhone 5s is a delight. Its hardware and software make it the best smartphone on the market. [AllThingsD]

AnandTech's Shimpi:

At the end of the day, if you prefer iOS for your smartphone — the iPhone 5s won't disappoint. In many ways it's an evolutionary improvement over the iPhone 5, but in others it is a significant step forward. What Apple's silicon teams have been doing for these past couple of years has really started to pay off. From a CPU and GPU standpoint, the 5s is probably the most futureproof of any iPhone ever launched. As much as it pains me to use the word futureproof, if you are one of those people who likes to hold onto their device for a while — the 5s is as good a starting point as any. [AnandTech]