I just realized that as I was making this blouse. Oh well, purple is good I guess.
So the collar was a bit of a pain, as many reviewers noted on http://www.patternreview.com/, but it's so important on this particular blouse. Of course I had to make it harder on myself and use velvet.
I underlined the main fabric with muslin because it was very sheer. I also underlined the velvet collar with muslin, to make sure it didn't come out floppy. It worked out well!
I'm happy with it. All I have left now are sleeves, a zipper and a hem!