The toggle switch is arguably my favorite feature. You can use it to quickly swap between the headset's individual speakers, and adjust each volume level independently -- the lighted dial around the volume knob indicates each level individually. There's a lot of freedom here; I found a sweet spot for every single setting, but I would've loved if there were some ability to save profiles -- one setting for multiplayer matches that keeps the rear speakers dialed up a bit, and a balanced setting for role-playing games, as an example.
Another great, oft-neglected feature of headsets is that speaker and headset toggle switch. There's a micro-usb port on one end of the volume control unit, where you can plug in the included speaker input dongle. Plug your speakers in to that, and you can automatically swap between headsets and speakers on the fly. I kept the headset on for games like Battlefield 3. In League of Legends, where pinpoint audio accuracy isn't necessarily a must (at my skill level, anyway), I swapped over to my speakers. The intricate volume controls don't work with standard speakers, but it's still a definite improvement over needing to set audio output sources manually in games, or in Windows.
A braided cable tethers the Tiamat to your PC. It's rather long, but I hate cables. Wires will negate any connectivity or fidelity issues you may run into with wireless headsets, but... I hate cables. It's a personal choice, really.
The audio jacks on the Tiamat's cable connect to your sound card (or motherboard), but there's also a USB plug that powers the volume control unit. I ran into some trouble here; a loud, annoying buzz filled the ear cups wherever I plugged the Tiamat in. Razer's FAQ explains this problem away -- every single one of my motherboard's USB ports apparently have a grounding issue. User experience will vary, but I needed an external USB adapter to get rid of the buzz.
Of some importance: the Tiamat looks really, really good. You won't ever see the subtle green glow or the bold, exposed drivers, since the thing is on your head. But rest assured that you look great.