I am planning on going. Though I had heard but never went to one before, so I can't tell you about pricing and selections.
As far as quality and whether they are worth it, I just recently bought a few past seasons thermal on sale, and I have to say that I love them. They are really soft and comfort. I am surprised that being as thin as they are, they keep me pretty warm. I am definitely looking to buy more thermals and also some hoodies.
I LOVE Primp, which is why I'm bummed that I can't make it to this.
I have just about all prints of thermals and jackets except for the newest ones (clover, pig, sheep, cameo, etc.) and LIVE in them. They're so soft and comfy and definitely worth the price. I love them a lot more than Juicy.
As for sizing, the thermals run large, tank tops are true to size and the jackets depend on what style they are. I have jackets in all sizes just because they're cut differently.
Kind of embarassing, but the attached pic is of my Primp stuff (not including my purple swallow thermal and the white thermal with the whales).
And oh ya I definitely do. It doesn't stay cold here for very long so I wear the heck out of my jackets and thermals when I get the chance.
That's why I like getting the tshirts too, then I can wear the prints when it's warmer also.