I've been incorporating Vitamin C serums into my daily skin care routine for almost a year now, and have tried multiple different brands across a large spectrum. In my experience, most of them have almost the exact same ingredients lists and product descriptions, just different labels/companies selling them. Generally, these serums have been safe for my sensitive skin but there have been a few select ones that have irritated my skin too much.
Fortunately, Amari's serum is a pretty standard serum that does not break me out and is great at evening skin tone and reducing dark spots. You can feel your skin soaking in the nutrients whenever you pat this stuff onto your clean face. Like any skin care product, you won't see instantaneous results, but you will definitely seem improvement if you use it consistently and take care of your skin (adequate cleansing, moisturizing, drinking plenty of water, etc.) in the long term. Remember, this serum itself is NOT a moisturizer, so you should always follow with one (a lotion, emulsion, oil, or anything like that) to lock all the healing properties in.