It's two things
When I took the Freestyle Edge's box in my hands, I was really surprised at how small it was. After all, in the pictures it had these huge wrist-rests on it. Those rests were included in the box, and it's a snap to attach and detach them. That is, they literally snap on. If this were something users were likely to do often I might have concerns about the durability of this process, but most likely you'll either attach the wrist-rests and leave them attached forever or leave them off entirely, depending on your typing style.
Wrist-rests attached, the Freestyle Edge is actually one of the deeper keyboards that I've used. That depth doesn't cause any usability problems—the keys are normally sized and spaced—but it could be an issue if you're really strapped for space on your desk. Fortunately, the split in the middle of the keyboard lets you position the halves however you like. Thanks to that flexibility, you could probably fit them in places where a regular keyboard wouldn't. Most folks will probably just angle the halves slightly outward, but hey, it's your keyboard. Have it your way.
One of the criticisms I could make about the Freestyle Edge is that it has no tilt or lift adjustments out of the box, not even dinky little snap-out feet. To get a three-dimensional ergonomic experience, you'll have to spring for the $25 lift kit. Kinesis sent me a set to try, and I have to admit that I am really glad for these feet. I'm not someone who normally uses tilt or lift adjustments on keyboards, so I wasn't going to order one. What a mistake that would have been.
The lift kits are a pair of multi-part stands that attach to the bottom of the keyboard halves near the center split. Once attached, you can flip around the free-swinging stands to adjust the keyboard's angle. Resting the keyboard on the stands in their default position provides a five-degree adjustment. If you want more height, you can snap the stands down in a "tent" to provide a ten-degree lift. If you still need more height, you can swing the snapped-together stands toward the inside edge of the keyboard and rest the halves on their longer feet to get the full 15-degree angle. After they're all set up, the stands are completely stable thanks to their rubber feet, and you would never know that they're not an integral part of the keyboard.
Without the lift kit, I simply used the board with its halves spread slightly and angled out to straighten my wrists. At that point, I was already impressed with the Freestyle Edge. My wrists felt looser and more relaxed, and even after gaming for hours I didn't have that familiar tightness in my left hand. Adding the lift kit just made things even better. It's difficult to describe the feeling if you've never used an ergonomic keyboard that declines toward the edges, and I certainly haven't done so long enough to make any appraisals of its long-term benefits. I can say that it just "feels" more natural, though.
That said, let me remark that I use the lift kit in its lowest, five-degree inclination. The image above demonstrates the full 15 degree incline that the kit can provide, and while it is quite stable in this setup, it doesn't work for my typing style. I'm sure this angle is very good for your wrists, but while trying to type this way I found that it was quite taxing on my forearms because you can't set your wrists on the palm-rests or they'll slide right off. Folks who don't rest their wrists on the keyboard while typing might be better able to enjoy this degree of lift.
The picture above is representative of how I typically use the Freestyle Edge. The split in the middle is useful as heck. Not only does it let you move the halves of the keyboard apart for improved comfort, but you can also set things in the middle. I often go back and forth between a controller and keyboard-and-mouse setup for the myriad games that I play, and sometimes even within a single game (like for piloting in GTA V). Having the ability to set the controller down directly between the halves of my keyboard is a huge benefit for someone like me.
It's also convenient for things like my smartphone, paper maps, documents that I'm re-typing, bowls of cereal, or really anything else you'd set on your desk in front of you. The cable linking the two halves can extend up to 20 inches, so even the most extreme splits should have plenty of slack. Honestly, I've been surprised just how much the split has become my favorite feature of the Freestyle Edge. This is true despite the fact that the split can actually be inconvenient as a gamer. Having a split keyboard like this makes it impossible to reach over to the right half with my left hand. I have to either remove my hand from my movement keys entirely, or lift my right hand from the mouse.
The split is eminently useful for typists, though. You can angle the halves of the keyboard toward your elbows to keep your wrist at a more natural angle. That said, the split has introduced a new kind of typo where I find the homing bumps on F and J and then completely screw up what I was typing because the keyboard is at an off angle. I also have some issues finding function and editing block keys without looking down at the keyboard. These are just sort of par for the course for this kind of keyboard, but they bear mentioning.
Kinesis talks up the ability to simply set aside the right half of the keyboard to make more mousing room, and that's probably useful for folks who are really into games like Call of Duty or CS:GO that don't require the right half of the keyboard. Even in those games you'll probably want to chat with your teammates, though. However, if you don't need to use text chat in your game you can certainly use the Freestyle Edge more or less like a Nostromo Speedpad or Razer Orbweaver.
Helpful for that use-case is the placement of the "fun cluster." On the far left half of the keyboard, you get eight dedicated macro keys, as well as the keyboard's Fn key and a clicker for toggling the backlight on and off. It's here where we get into one of my many niggles with the layout of this keyboard. You see, above the fun block there's a double-width Escape key. At first, I found this convenient since I often have to mash Esc to exit multi-layered game menus or skip cutscenes.
On most keyboards, though, Esc is directly above the backquote-and-tilde key. It's easy enough to get used to the new placement of Esc on the Freestyle Edge, but its position still means that the whole standard function row is moved over one step. This shift is still screwing me up even as I write this article. It's a major frustration for someone who uses the F-keys a lot, but for someone who doesn't it may not be a problem. I'm slowly getting used to it, but I'm not there yet.
The Fn key on this keyboard is a toggle, so it works as a "lock" rather than as a shift. There's even a light for it over on the opposite half of the board. Thanks to its toggled nature, the media controls on F1-F6 are very easy to use. At first, I was frustrated with the distance between Fn and the media functions, but once I realized you don't have to hold the Fn key to use those keys, my concern was assuaged. The Fn key is actually more powerful than just that, though. It can shift the whole layout of the keyboard with the right configuration. I'll talk more about that programmability in a moment.
Over on the right half of the keyboard we have a fairly standard layout, disregarding the compressed editing block along the right edge. There are four extra buttons on the top for accessing the keyboard's programmable functions, and four "lock" lights in the top right. Usually I would nitpick this keyboard for having both right Alt and Ctrl keys rather than swapping one of those for a context menu key. Given the keyboard's split nature, though, it would be virtually impossible to one-hand Alt or Ctrl shortcuts using the alphanumerics on the right side without the second set of modifier keys.
I will complain about the way Kinesis laid out the editing block, though. Home, End, Page Up, and Page Down are along the right side of the keyboard, which is neither here nor there. Print Screen, Scroll Lock, and Pause/Break ended up on the top row along with the F-keys where they belong. However, the Delete key is up there with them. I don't know about you, gerbils, but I make a lot of typos, and I use the delete key more than anything else in the editing block. Some old Microsoft ergonomic keyboards actually came with a double-height Delete key just for that very reason. I have pressed Home when going for Delete far too many times on this keyboard.
Fortunately, most of these gripes about the Freestyle Edge's layout can be resolved using the SmartSet feature. Head on over to the next page where we'll look at the Freestyle Edge's programmability functions.