Features of the new iPhones Exterior design Upgraded camera Touch ID A more helpful Siri 64-bit chip iPhone 5C colors Early reviews positive for the iPhone 5S "The best smartphone on the market," says one reviewer Some say fingerprint scanner is significant, not a gimmick iPhone 5C called "iPhone 5, but colorful plastic" (CNN) -- So much for being underwhelmed. After Apple's two new iPhones -- the 5S and 5C -- disappointed some observers when they were unveiled last week, the first round of reviewers are now rendering their verdicts after spending time with the devices. And in contrast to initial reactions, which included yawns from tech sites and a dip in Apple's stock price, the first wave of reviews are largely singing the praises of the new phones -- particularly the top-of-the-line iPhone 5S, which comes packed with an upgraded 64-bit processor, souped up camera and Apple's first-ever Touch ID fingerprint-scanning system. Many noted that, like the iPhone 4S before, the 5S is more of an upgrade of the 5 than a radically new device, a fact that probably led to a lot of the mixed initial response. But under the hood, many say the iPhone 5S is truly different, and one reviewer is even calling it the best smartphone on the market. Here are some of those reviews. Unless otherwise noted, the reviewer is referring to the iPhone 5S. Walt Mossberg, All Things Digital The iPhone 5s is the first digital device I've seen with a simple, reliable fingerprint reader -- one you can confidently use, without a thought, to unlock the device instead of typing in a passcode. ... It sounds like a gimmick, but it's a real advance, the biggest step ever in biometric authentication for everyday devices. 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 ... . Overall, however, the new iPhone 5s is a delight. Its hardware and software make it the best smartphone on the market. Darrell Etherington, TechCrunch Apple has worked some behind-the-scenes magic with its latest and greatest, and made some design changes for the better, too, all of which adds up to a new smartphone market king. At first glance, it's easy to dismiss the fingerprint sensor as a whiz-bang feature designed to attract eyeballs and do little else. But this isn't that. ... It feels like a mature feature that actually enhances the overall experience of using an iPhone in a noticeable way that you encounter very frequently. The hardware may resemble its predecessor in many key ways, as with the 4-inch Retina display, but it improves dramatically in areas like the camera where it makes the most difference to every day users, and in the addition of the fingerprint sensor, which is already a feature I miss when I switch back to older generation devices or the iPhone 5c. Anand Lal Shimpi, AnandTech Like the S-devices that came before it, the iPhone 5s is left in the unfortunate position of not being able to significantly differentiate itself visually from its predecessor. ... I think gold is likely the phone I'd opt for simply because it'd be very different than everything else I have, but otherwise space grey is probably the best looking of the three devices to me. It remains to be seen the impact display size has on iPhone sales. Anecdotally I know a number of die hard iPhone users who simply want a larger display and are willing to consider Android as a result. I still believe that users don't really cross shop between Android and iOS, but if Apple doesn't offer a larger display option soon then I believe it will lose some users not because of cross shopping, but out of frustration. 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.  David Pogue, New York Times If we're reaching a point of diminishing returns in hardware breakthroughs, the software breakthroughs are only just getting under way.The new iPhones come with iOS 7, a redesigned operating system. ... This software looks nothing like the old iOS. It's all white and clean, almost barren. ... You might love this design, and you might loathe it. You also might get used to it. But in any case, iOS 7 is more efficient to navigate, because nothing on the screen is eye candy; everything is a button, so you spend less time hunting for things. If you wanted to summarize ... here it is: 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. On the iPhone 5C: "It's essentially identical to last year's iPhone 5, except that its back and sides are a single piece of plastic instead of metal and glass. It's a terrific phone. The price is right. It will sell like hot cakes. ... But just sheathing last year's phone in shiny plastic isn't a stunning advance. Lauren Goode, All Things Digital On the iPhone 5C: "You've seen this phone before. Sure, it has a new name: iPhone 5c. And its plastic body comes in different colors. It also has an attractive price when tied to a wireless contract. But the 5c is really a slightly improved iPhone 5, which Apple is no longer offering. While the 5c looks and feels very familiar, it's still a good phone and an improvement over the 5. But its improvements are evolutionary, not revolutionary. Myriam Joire, Engadget Though it's easy to dismiss this handset as iterative, the 5s is the first smartphone with full 64-bit support and a capacitive fingerprint sensor, and it also ships with a fresh, revamped version of iOS. This might not matter to folks who were content with the status quo, but it matters a lot to Apple -- and to the company's future as well -- especially if the company wants to fend off an increasingly fierce pack of competitors. 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.