Experience
Whenever I am considering purchasing a perfume, I check Dossier first to see if they have a reasonable dupe. My first Dossier purchase was "Floral Marshmallow", which is inspired by By Kilian's "Love, Don't Be Shy" – at less than 20% of the cost! The bottle isn't anything special, but it's not an eyesore either. It looks right at home on my vanity next to some more expensive fragrances. I appreciate the weightiness of the bottle as well as the magnetic closure. Sometimes, these dupe fragrances can be very short-lived, but I find that my Dossier perfume lasts all day.
Feedback
Just more options! They have a really solid variety, but it's always a bummer when I'm looking for a particular dupe and they don't offer it. Also, I appreciate the free returns, but would love to be able to order samples.