Let's talk about this d-pad situation
There is nothing I can write about this d-pad on this mouse that everyone will agree with. We've had sufficient spirited debate on its merits just within the TR ranks.
One point of contention is that, like the OLED display, the d-pad might just be a marketing gimmick. The assertion is that it's merely a four-button cluster, like any other mouse that has extra programmable side buttons, but with a more sensational name. On the other hand, you could say that these buttons are specifically meant to evoke a d-pad—which is to say, Cooler Master presumes that people will map some of the d-pad inputs you find on a game controller to these buttons, in a similar layout. I'm of the mindset that Cooler Master created this button array for the latter purpose and that we should evaluate it as such.
The first question, then, is whether the company got the hardware right. The second question is whether or not there's a point to having a d-pad on your mouse.
Let me feel those buttons
To the first question, I would answer with a resounding "almost." Usually, mouse side buttons are light, which for the most part is desirable. You don't want to have to offer more than a gentle nudge of the thumb to navigate forward or back while you're browsing online, after all. They're also usually longish and thinnish. By contrast, d-pads are typically more centered and symmetrical and require more force to actuate.
The d-pad on the MM830 is, unfortunately, not symmetrical. Instead of a cross with four arms of equal lengths, each arm is a different length. I (think) I understand that Cooler Master fiddled with this layout to accommodate the way your thumb would lay on the side of a mouse versus on top of a controller's d-pad, but when you get right down to it, the thumb lays exactly the same. It's just that the mouse's d-pad and your thumb are 90° from where your thumb lays on a controller's d-pad.
In other words, it would have made more sense from a layout perspective to copy and paste a regular d-pad to the side of the MM830. Instead, Cooler Master inexplicably pulled and stretched the arms until they were asymmetrical. The decision on where to place the rearmost button of the d-pad is particularly curious. It's really hard to strike it; you have to rock your thumb back and press it with your inside knuckle. That's odd and not especially comfortable, and it makes no sense to put it there.
The bottom button of the d-pad is also kind of tough to hit. There's a sloping thumb rest on the side of the MM830 that, for the record, I like just fine, but that button sits on part of the slope. The slope partially blocks my thumb when I try to hit the button, which is frustrating. You're supposed to be able to swish through the d-pad with one gesture, but the MM830's d-pad simply makes that impossible.
The d-pad has other things going for it, though. In addition to the firmer feel, the buttons are stylized, with squared-off ends. It's a pronounced tactile experience all the way around, and I like how that feels.
So then, what we have is a half-baked d-pad experience: The layout is off, but Cooler Master more or less got the actual buttons right.
What do you even need a d-pad for?
Hardware considerations aside, it's fair to ask why you would need or want a d-pad on your mouse in the first place. D-pads on game controllers are usually on the left, after all, whereas you have to use your right hand to use it on the MM830. Thus, even if you can map d-pad controls 1:1 from a gamepad controller to this mouse, your muscle memory doesn't translate. Plus, as some have pointed out, if you want d-pad controls while you're gaming, just use a freaking game controller.
To an extent, that's obvious, but I've been around long enough to know that the way each individual works out their input devices, button mapping, settings, macros, and even lighting is extremely subjective and personal. Sure, maybe you're not going to find millions of people who have been dying for a mouse with a d-pad to program, but it's all but guaranteed that a certain number of folks will be over the moon about it.
It seem clear that the intent is to use the d-pad for gaming. We'll get to that in a moment. But let us not overlook those who, like me, generally use the same mouse for work and gaming and will plan to assign functions to those four buttons. I pretty much can't rock without at least forward and back nav buttons on a mouse, so that's a must for me.
Unfortunately, the MM830's layout makes this a far less pleasant experience than you get with typical nav buttons. As I mentioned, the back button is just too far back; I wish it was moved up maybe a centimeter. The placement of the forward nav button is fine, but its firmness and stylized shaped make it a little tougher to press than I'm used to. I can't just lightly squeeze my thumb to actuate it. (I've said all that before; but in this context, it's not a good thing.)
Alternatively, you could program the top and bottom d-pad buttons for forward and back navigation. Regardless, I do like having an extra couple of buttons for macros and miscellaneous functions. Of course there are myriad options. I played with various button assignments, with mixed results. For example, my favorite keyboard command of all time is Alt + Tab, but you can't actually program it with Cooler Master's Portal software. (More ranting on that in a bit.) But, for instance, I found that setting the up arrow on the d-pad to Ctrl + C and the down arrow to Ctrl + V was super handy.
On the whole, though, the MM830 isn't a productivity mouse. The d-pad is too much of something and not enough of something else.
Is it a different story for games? Well, I always feel a little more comfortable moving my fingers around on my mouse buttons versus the keyboard; I get all locked into the WASD cluster and have to think—even for the briefest of brain cycles—about other keys. (Yes, I'm trash at gaming.) I'd much rather use extra mouse buttons even for things like reloading, specials, grabbing stuff, and so on.