In her wonderful book, Old Food, Jill Dupleix includes her own recipe for Sachertorte, which has the merits of being "easier" and "faster", than the original, and most importantly, needing "no return airfare". This is obviously a different story when you're actually in Vienna. I do believe that it would be a culinary crime to visit Vienna without trying the original Sachertorte.
The Hotel Sacher is located in the centre of town, right opposite the Opera House, and the cafe is directly accessible from the street. It's very quiet and calm, with understated decor and unobtrusive waitstaff.
Interior of Cafe Sacher
So moving on, here's the cake! The 2 of us shared a slice (it's rich and expensive, you see), and it was lovely!
It is rich and undeniably chocolatey, but not overpowering or super-dense, like so many chocolate cakes you can get these days. It's got a great cakey texture, it's not too bitter, not too sweet... in fact, I might say it's just right. And worth the return airfare!