The Stay In Line Lip Liner in Luminous color by Jason Wu Beauty is highly praised by Ruby in their video review. Ruby mentions that the lip liner is creamy and comfortable, making it easy to apply. They also note that the color is stunning and love how blendable the formula is. Overall, Ruby finds the lip liner to be a great product, highlighting its comfortable and easy-to-use formula as its main benefits. However, no potential drawbacks are mentioned in the review. Based on Ruby's positive feedback, the Stay In Line Lip Liner in Luminous color by Jason Wu Beauty seems to be a high-quality and enjoyable cosmetic product.