In WoW, we don't get to decide much about our characters. A few pre-built faces and skin tone are about as deep as the customization options run. Gear is typically released in discrete tiers, and you'll find that most Rogues use mostly the same leather sets. Talents are similarly stale: there are rarely true choices in our trees. Choosing one talent over another either cuts your damage or cuts your usefulness, and for most Rogues the decision is easy.
Most people assume one Rogue is as good as another. Take two arbitrary Rogues, Gankenstein and Istabbedu. They're both undead Rogues: their chins are falling off. They're both sporting full Season 2 gear with a few PvE epics sprinkled in. And they both traded in their Slicers for Shankers & Shivs this patch; all aboard the Mutilate train. So what separates these two from each other, and from the other 9,000 Rogues on any given server?