The iPhone 5s is here, along with the new Touch ID fingerprint ID sensor, Apple A7 processor, M7 motion coprocessor, much improved iSight camera, and more LTE data support than ever. The best phone in the world is only as good as the carrier it's connected to, however, so for the last few days I've been testing it on AT&T in the U.S., and in several categories including call clarity, data speeds, tethering capabilities, and more. Does the updated LTE support that Apple is calling UltraFast really make a difference on AT&T? Are their any improvements over last year's iPhone 5, and if so, are they substantial? Let's find out!

Network reliability and dropped calls

I haven't see a change in overall dropped calls when on the iPhone 5s over the iPhone 5. I never really experienced very many dropped calls on the iPhone 5 either. I did, however, go back to a few of the areas that had given my iPhone 5 problems and they are still an issue with my iPhone 5s, which leads me to believe it has nothing to do with the actual phone hardware I'm using and is actually a network issue (most people I know complain about service problems in these areas as well). So far, there's nothing the iPhone 5s does that's especially better than my iPhone 5 when it comes to less dropped calls.

As long as you're in an area with good service, your iPhone 5s should be rock solid.

Call clarity

I live in an area that is converting to LTE. Around my house is still spotty, but I can go 10 minutes in any direction and get full bars of LTE. For these tests I spent time in regular HSPA+ areas as well as LTE areas. When I had HSPA+ (which AT&T insists on calling 4G), I noticed no discernible difference when it came to call clarity. However, when I was in a strong LTE area, I noticed that my iPhone 5s seemed slightly clearer. The caller on the other line said they couldn't tell a huge difference, but could almost always pick out when I was using the iPhone 5s.

If you're in an AT&T 4G area, you won't notice much of a difference between the iPhone 5 and iPhone 5s. If you live somewhere with excellent AT&T LTE coverage, the iPhone 5s has slightly better call clarity, but only slightly.

Data coverage and reliability

AT&T is a funny thing in my area. We have spots that are really good, and then spots that are really bad. I'm talking spots where I have a full bars of 4G signal but not enough back-haul on the tower for anything to actually download. Because this is a problem on AT&T's end, it's not surprising that they carry over to the iPhone 5s. Most of us have just learned to live with it, since overall, AT&T remains one of the best choices in our area.

From the standpoint of reliability, I've experienced about the same signal strength I've always gotten with past iterations of iPhones. The difference really comes in with data speeds themselves, which I bet is what you're most interested in anyway...

Data speeds

I decided the best way to test data speeds on the iPhone 5s would be to compare them to the iPhone 5 under the exact same conditions. And just for fun, I threw the iPhone 5c into the mix as well. From left to right above, you have SpeedTest results for the iPhone 5s, iPhone 5c, and finally the iPhone 5. As you can see, the iPhone 5s consistently pulls in faster data than the iPhone 5. When it comes to the iPhone 5c versus the iPhone 5s, both pulled in similar speeds but I found the iPhone 5s to be more consistent at keeping the tops of those speeds.

When tethering a laptop or other device using the Personal Hotspot feature, I don't see any noticeable difference except the iPhone 5s seems to push consistently faster, as it does on its own. Using SpeedTest on a tethered device, I noticed little difference except that the tethered device clocked in at a few megabits less, which is to be expected.

If you live in an area with LTE coverage, the iPhone 5, 5s, and 5c get blazing fast LTE coverage. But if you want the fastest data you can buy, the iPhone 5s and iPhone 5c continually out-performed the iPhone 5 for me when it comes to sheer speed.

Battery life

My iPhone 5s has consistently gotten better battery life than my iPhone 5, particularly on iOS 7. Considering the iPhone 5s has a slightly larger battery, I'd attribute most of this, if not all of it, to that. There isn't a noticeable enough difference to write home about though. I'm not by any means disappointed in the battery life but I'm not particularly wow'ed by it either.

If you're coming from an iPhone 4s or earlier, you'll be impressed by battery life. If you're coming from an iPhone 5, expect it to be about the same. At least if you're on the AT&T network.

How to fix battery life issues with iOS 7, iPhone 5s, and iPhone 5c

The bottom line

For AT&T customers considering a move from an iPhone 4s or earlier to an iPhone 5s, you'll be blown away by the speed difference if you're in an LTE area. If you have an upgrade, use it. Apple's claims of UltraFast LTE in the iPhone 5s and iPhone 5c are very real.

If you're an iPhone 5 user on AT&T, the upgrade is by no means a no-brainer. LTE will only be a factor in other countries where the new bands provide support in places the old bands never did. If you do want to upgrade, the Touch ID sensor and new iSight camera are probably more compelling reasons.

More on the iPhone 5s

We all know that carrier coverage and reliability can change dramatically given geographical location. If you've got an iPhone 5s running on AT&T's network, be sure to let us know your experiences with it compared to your last smartphone via the comments below!