I have the Tough Case, just delivered today. It's similar in design to the Otterbox Commuter -- a thin silicone base layer covers the entire phone, while a hard plastic shell snaps around the back, sides and corners.
Pros: The fit is absolutely perfect. The silicone layer over the buttons is just the right thickness -- the power, volume and camera buttons are all covered, but their function is not impeded in the slightest. I was particularly delighted by how well the camera button works, no interference with function or sensitivity at all.
Around the front edge, the silicone layer rises a few millimeters above the screen, so you can comfortably place the phone face down without worrying about scratching the glass. Similarly, the camera lenses and flash are deeply recessed on the back, with perfectly sized openings around each (which, IMO, is how the lenses should've been on the phone itself). You can drag your phone across concrete with no worries, if that's the kind of thing you're into.
The hard plastic outer layer has a smooth matte coating that makes it feel more like silicone than hard plastic, giving it a very nice feel in the hand. It's also covered with a raised, textured pattern, making the phone very unlikely to slip out of your hand. By contrast, the Otterbox Commuter I briefly had on my Hero had a plastic outer shell that was slick and shiny, and the phone slipped out of my hand twice within the two days I left it on (which is why I used it only briefly).
Cons: My only real complaints are aesthetic. I really like the slim, refined look of this phone, and the grippy, textured, matte black surface of this case, while very protective and easy to hang on to, is a tad inelegant, giving the phone more of an industrial feel. It also adds a bit of bulk, which was immediately noticeable when I pocketed the phone with it on (although I will say it's positively svelte compared to some of the other cases I've seen pictured on this forum). The phone does also feel noticeably heavier with this case on.
In response to the OP, the case does have a couple of mysterious ports at the bottom. One lines up with the slot you use to pry the battery cover off, while a smaller one lines up with a tiny hole just to the left of the other (edit: duh! that's the mike, thanks minieod). I don't know why those are there, but they don't do any harm.
Overall, I'd say thumbs up. If you like the basic design of Otterbox cases but want something slimmer than the Defender and easier to hold than the Commuter, this is probably your best choice.