I'm not going to go over the entire Nostromo deal. I think Phaelia does a great job here. I'm just going to give you my parry, dodge and spin on it.
Why did I decide to go to a Nostromo? I was tired, oh so tired, of hitting Sinister Strike as quickly as possible over and over again. I don't have tendonitis or carpal tunnel and I don't want either. So, when I felt the first twinge of something in my left hand from hitting my  key over and over again, I decided that maybe something needed to be done.
My goal with using my Nostromo is two-fold: 1) eliminate hand stress and 2) consolidate the majority of my play onto my Nostromo and mouse, the keyboard is simply for chat and nothing more.
As you might see, my key layout may seem a bit strange. My Nostromo layout evolved from my normal keyboard bindings: Q for Stealth (as it is right next to the movement), X for Sprint Riposte (I no longer use Riposte in my build), etc. I haven't bothered remapping them to something that makes more "sense" as it allows me to switch back to full keyboard and know where pretty much everything is still.
My Nostromo layout
But those are just the keys that are bound. Honestly, it doesn't matter one way or another which key you have mapped to the nostromo except for the "modifier" keys such as "alt","shift" and "ctrl". That is as long as you then map your action buttons in World of Warcraft to the same keys.
I've mapped my functions in the following way:
Hopefully, everything is pretty self-explanatory. SS is Sinister Strike and CoS is Cloak of Shadows. But you already knew that, right? Beatdown, Stun, Bleed, Feint and Stealth are all WoW macros described below.
I've used the outer 3 right keys and outer 3 left keys for system functions regardless of my character. Having esc and tab enables me to quickly handle targetting and escaping out of whatever dialog I'm in. Character, Map and Backpack are also essentials for allowing my left hand to remain on the Nostromo for all my functions. I've also mapped the mousewheel on the Nostromo to my Social window to determine who is on in guild, the Quest window and I use the forward turn of the mousewheel for my mount with a shift+forward mousewheel for my flying mount.
The backstab key, the fourth key in the top row, is the one key I have a Nostromo macro on. I've setup the macro like this:
So, it's basically spamming the key over and over again every half second as long as hold down the key. I use this with Backstab Sinister Strike,shift+key for Sinister Strike and alt+key for my cast sequence of Blade Flurry, Evasion and Adrenaline Rush. I use this on every character for whatever ability I need to hit over and over.
Next, I have created the following macros to further consolidate functionality. Most are based so that they do one function in stealth mode and another outside of stealth. And the Stealth macro is mashable. You have to press alt+stealth to get out of stealth and you press shift+stealth for Vanish.
/cast [stealth] Sap;Slice and Dice
/cast [stealth] Garrote;Rupture
/cast [stealth] Pick Pocket;Feint
/cast [stance:0] Stealth; [stance:1, modifier:alt] Stealth; [modifier:shift] Vanish
/cast [stealth] Cheap Shot; Kidney Shot
/castsequence reset=120 Blade Flurry,Evasion, Adrenaline Rush
Finally, I use the mouse for steering and the directional pad for strafting and backwards movement. Further, my mouse has four buttons and I've mapped the far right button to autorun and the far left button to my Ventrillo speak button.