To see how it stacks up against the competition, I pit its specs against the iPhone 5, the new HTC One, the Nokia Lumia 920 and the Google Nexus 4. It's a brief comparison for now, but bookmark this page and check back soon for a full, exhaustive test once we've given it the review treatment.
The S4's design is perhaps the most unremarkable aspect of the new phone. It hasn't been updated much from the S3's look, which isn't likely to please those of you who scorned Apple for being similarly unambitious with the iPhone 5.
Crucially, it keeps the plastic construction -- something of a contentious point for those who argued the S3 felt cheap. Both the iPhone 5 and HTC One use metal chassis, which feel very classy to hold and quite a lot more sturdy. The Lumia 920 uses a solid polycarbonate frame -- a kind of upmarket single piece of plastic -- which again feels more solid than the S3 did.
On the flipside, the plastic frame of the S3 made it very lightweight and the S4 is marginally lighter still. The S4 might be the better option if weight is an issue for you. At 7.9mm thick, it's slimmer than the S3 too and considerably more svelte than the comparatively chubby Lumia 920 and Nexus 4.
The single home button remains intact at the bottom on the front, a feature that prevails on the iPhone as well. The 920, Nexus 4 and HTC One all use touch-sensitive navigation buttons instead.
Samsung has upped the screen size to a palm-stretching 5 inches, up from the 4.8 inches of the S3. It's only a tiny bit extra, so I doubt you'll notice the difference. The Nexus 4 and HTC One both have 4.7-inch displays, while the iPhone 5 brings up the rear with a much more modest 4 inches. If you want screen real estate to watch video, the S4 is the one for you -- so long as you have huge hands.
It's got a Full HD resolution, which is only rivalled in this roundup by the HTC One. The One is slightly smaller though, so its screen will be marginally sharper as it's packing in the same pixels into a smaller space. I almost guarantee you won't be able to tell the difference though.
Samsung generally has a good record of producing vibrant, bright screens, so we'll have to wait and see which display looks more pleasing to the eye.
Arguably the headline feature of the S4 is its processor. It boasts an astonishing eight processing cores. That's double the amount you'd find on the S3, or even the HTC One, Nexus 4, or any other top-end smart phone out there right now. It's clocked at a mighty 1.6GHz too, so you can confidently expect it to output some monstrous power. We haven't been able to put it through our usual barrage of brutal benchmarks, but we're certainly excited to get our hands on it.
The Lumia 920, meanwhile, uses a much more understated dual-core processor, which I found perfectly nippy for most tasks. There's not that much you can really do with a Windows Phone that'll stretch it though, so it's difficult to hold the weaker processor against the 920 too much.
Samsung has bundled its new blower with a handful of new software treats too. Its ChatOn messaging service now supports three-way video calling as well as screen sharing -- something we've seen before on the new BlackBerry Z10. You'll also get built-in translation tools for those times when you need to send a crucial email to your German buddy.
There's also a load of gesture-based controls too. Waving your hand over the screen lets you do things like skip songs, scroll through Web pages and answer calls. Waving your hand over any of the other phones will just make you look like a fool. We'll have to go hands-on (or hands near) with the phone to see whether this feature is any use in everyday life.
The S4 is running on the latest version of Android, known as 4.2.2 Jelly Bean. It features Google Now, Photo Sphere, built-in photo editing and a host of other treats. The HTC One uses 4.1 Jelly Bean, so you'll be missing out on Photo Sphere, but everything else is much the same. As a reference device for new Android versions, the Nexus 4 already boasts the latest software and will be among the first to receive the next update, to Key Lime Pie. The others will likely have to wait quite a while.
Around the back of the S4 is a 13-megapixel camera, the highest number of megapixels offered by any camera in this group. The Lumia 920, Nexus 4 and iPhone 5 all have 8-megapixel snappers while the HTC One has a rather low 4 megapixels. Numbers aren't everything though, as HTC claim its pixels are bigger and therefore better. It didn't impress me much in my review though.
The S3's camera was good, but didn't match the iPhone 5's in terms of colour depth and HDR prowess. We'll have to wait and see if Samsung has managed to up the image quality as well as the pixel count.
To help tip the scales, it's loaded up the camera with a host of features. Drama Shot combines an action moment into one frame -- exactly the same thing as we've just seen on the HTC One -- while Cinema Photo allows you to selectively animate one portion of a scene to create a looping gif. Again, that's lifted straight out of the Lumia 920 and can be done with the Cinemagram app on the iPhone 5.
There are a bunch of other little additions too, along with the usual selection of scene modes. It's good that Samsung has whacked in some camera goodies, but it doesn't seem to be bringing anything new to the table that you can't find on the other cameras. If it wants to show off its photography skills, it's going to need to capture some great shots without relying on gimmicks.
The one area the S4 really stands out above the competition is its eight-core processor. It's likely to be phenomenally powerful, but whether that power really makes it a better phone than the rest remains to be seen.
Its software tricks and its camera additions are sure to keep Galaxy fans happy for a little while, but it's disappointing not to see Samsung play with a metal design, especially as swanky metals are in place on two of its main competitors.
How do you think the S4 stacks up against the rest? Let me know your thoughts in the comments below and over on our Facebook page.