for what its worth they are not "just" a DB interface layer. they are at this point or soon to be one of the most popular ORM in JS (~100% market share for new projects among early adopter types) and a cross-db "super ORM" at that (ya i know what i typed, i have my doubts too but hey that seems to be what people want).

also other features mentioned here https://news.ycombinator.com/item?id=34477321