Cuir d'Arabie is great. It has a strong, bitter opening that can be a bit jarring, but the leather+aoud combo seems to work beautifully together after that. Can't say I can compare it to any other leathers, it's more aoud than leather to me. Pretty much exactly what you'd think it would smell like.
After testing many of the Montale's (the aoud-based Montales I should say), I have to say that most of them smell like slight variations on each other (which I'm sure everyone else would agree with). A few of them stand out a bit, but otherwise I'd never need more than one or two of them. If you want something really strong, Black Aoud or Aoud Lime are the way to go. Softer interpretations might be Original Aouds, which is my fav.