1. It is an excellent mineral oil substitute and gives smoothness to products for example a cream with almond oil will be smoother and easier to apply compared to mineral oil (Journal of the American Oil Chemists, pg435-437, 1978)
2. It is odourless and chemically stable and therefore lasts for a long time ( Journal of the American Oil Chemists, pg 406-408,2007)
3. In a small study, when used in aromatherapy, it was shown to boost the immune system (Evidence Based Complementary Alternative Medicine, pg 179-184,2005)
I haven't really found anything particularly profound for its use in hair (like moisturising effect of coconut oil or sealing effect for jojoba oil) but some research is better than none at all. The one caution (which pretty much applies to everything natural) is that sweet almond oil does vary depending on where it was grown (Journal of Agricultural Food Chemistry, pg 4096-4101,2008).
Do you use almond oil? Is it any good?