I purchased the Guide Eyeliner Duo and my first impression was excellent. Once you get the hang of it, it's actually quite genius! Makes eyeliner application flawless for those of us with unsteady hands. There's plenty of education/tutorials on the brand website, which I found to be really helpful.
Would love to see a scannable qr code on the packaging so that relevant tutorials can be accessed quickly/easily. I am not a big fan of the Guide Gel Eyeliner formulation. For me it was clumpy and the product felt a bit dried out. I haven't tried the tool with any other brands, but plan to do so!