All my past relationships were based solely on sex. And its always been great but its never enough to keep me around. Its nearly impossible to find a complete package I think. You gotta sacrifice one thing or the other.
There is no sacrifice....as you said, you based you relationships solely on sex...
So you never got to know that person (nor did she get to know you), and when you eventually did...you didn't like what you saw...or you two didn't "fit".
Today's women, create "instant relationships" with men by just letting you "get it in" real early...no wooing, courting, so you two don't really know one another.
Now, you have listed this woman's attributes, and it seems that it far outweighs her "not being pretty enough" and her "Adele like looks", but if you look at Adele's face, she is pretty cute (with makeup on of course).
As long as she is not a whale, and she has your best interest at heart, I'd say go for it, and chances are you'll be in a happier place, unless you eff it up.