There seems to be a bit of confusion regarding the taxanomic classification of Aeonium arborescense. So, I'll leave it at probably in the Crassulacae family, possible genus Crassula ovata, species Aeonium. This is stated otherwise in more than a handful of references. So, not to be "hung up" on this I'll move on to why we like, how to care for, and what to expect from Aeonium.
This plant is enamored for the foilage. All are rosettes of perfect form...some are almost pancake in form and look like a terantula because they have so many "hairs" on the leaves (A.tabuliforme). They come in a crisp spring green (A. glandulosum), ruddish red almost black (A. arboreum 'Zwartkop'), and some are variegated (A. glutinosum or A. 'decorum Sunburst').
Aeonium are native to the Canary Islands, Morocco, and Madiera. This tells us that they aren't going to like to freeze, they will likely melt in several days of heat over 90o F, and will grow best with more moisture than a cactus, and in well drained soil. In highly protected Las Vegas "patioscapes" they will survive in the ground as long as the human care giver protects the plant a bit in severe weather. Click on this link to see lots of pictures of Aeonium.
Reference material: Sajeva, Maurizio & Costanco, Mariangela. Succulents The Illustrated Dictionary, Portland: Timber Press, 1997. Print.; Flora Gardener's Enclyclopedia. Portland: Timber Press, 2003. Print.