First and foremost, this GS4 variant will act a lot like a Google Nexus-branded device, but without the actual Nexus branding. That means it will run a clean, unaltered version of Android 4.2.2 when it ships. Some call it stock Android; it's the way Google envisions Android should look, feel and behave. The biggest benefit this offers is timely system updates. As with the other Nexus gear out there, the naked GS4 will receive system updates as soon as Google prepares them. For users who always want to have the most recent version of Android, this is the way to go.
Further, it will have an unlocked bootloader. This means owners won't have to root it if they want to install custom operating system builds. Most Android handsets ship with a locked bootloader, which makes installing custom ROMs a troublesome process that requires rooting. Rooting carries a small risk of bricking the handset. Owners of this unlocked GS4 won't have to worry about performing that step should they decide to modify the software.
[ For more news from Google I/O, see Google I/O: Where's Android? ]
By ditching TouchWiz and sticking with stock Android, this version of the GS4 loses a lot, too. Some of the best features of the Galaxy S4 are the innovative applications and features added by Samsung to the base Android experience. Take the camera, for example. The Google GS4 won't have any of the fun and creative shooting modes offered by the Samsung GS4, such as Drama Shot, Eraser Shot, Best Photo, and others. In fact, the stock Android camera is a fairly simple affair. Along with the camera innovations, you can say goodbye to Samsung's Story Album app, which lets you create digital photo albums and order prints.
Other missing features include the TV remote control software and WatchOn, Samsung's video discovery service. No Air View and Air Gesture for interacting with the screen without touching it. No Smart Scroll or Smart Stay for using your face and eyes to control the browser or video content. No S Health to monitor your activity, exercise and food intake. Last, no multitasking in multiple windows on the screen.
You do get an excellent piece of raw hardware, though. The GS4 has a fantastic 5-inch HD display, quad-core processor, 13-megapixel camera, expandable storage, LTE 4G and so on.
Ah, but what about the price? If you want to buy the Samsung Galaxy S 4 from AT&T, Sprint, T-Mobile USA or Verizon Wireless without signing a contract, they'll ask the same $649 for it. That's the actual retail cost of the phone. (Remember, U.S. operators subsidize the cost to get the price point down to more palatable levels.) For many, that $649 is worth the cost to get an unlocked device running a stock version of Android. (It's also the same price you'll pay to buy an unlocked version of the Apple iPhone 5.)
If $649 is too pricey but you still want an unlocked, stock Android device, Google still sells the LG-made Nexus 4 for $299/$349.
In the end, it boils down to your priorities. If you're the type who likes to tinker with your handset's software, either the Nexus 4 or the Google Galaxy S 4 is a fine choice. The GS4, however, gives you LTE, a better camera, and a better screen when compared to the Nexus 4. If you're not into modding your device and you might miss the features added by Samsung, then stick with a regular version of the Galaxy S 4 sold by the carrier of your choice.