Yes, jojoba oil can be used as a serum. Its composition is similar to skin's natural sebum, allowing it to absorb easily and provide hydration without clogging pores. It can be used alone or mixed with other serums.

Many dermatologists recommend jojoba oil for its moisturizing and anti-inflammatory properties. It's generally considered safe for most skin types, including sensitive skin, and can help with conditions like acne and eczema.

There isn't a single 'no. 1' face serum, as the best serum depends on individual skin concerns. Popular and highly-rated serums often contain ingredients like vitamin C, hyaluronic acid, or retinol, addressing concerns like aging, hydration, and brightening.

While generally safe, a potential disadvantage of jojoba oil is that some individuals may experience allergic reactions, although this is rare. Also, because it's an oil, it might not be ideal for those who prefer a completely oil-free skincare routine.