If I told you, it wouldn’t be a secret, now would it?
My experiences have varied. I’ve gone in VS before and found lots of cute stuff, but on one occassion I visited a VS where everything seriously was sized for 12-year-olds. I have no idea why 12-year-olds would need black lace teddies and see-through underwear, but there it was. I’m not a big girl (I wear size 4 jeans and a 36C) but I looked like a giantess in comparison.
I don’t have enough money to shop there on a regular basis, but I’m really not too happy about their panties. They don’t seem to fit me well–they don’t provide enough room for my substantial booty. Also, the width of the part between your legs seems fitted for someone with, erm, more generous labia than I have; there’s a lot of extra fabric that just kind of hangs down. Maybe I need to redistribute some of my butt fat?
You sure you’re not putting them on backwards? 
I’m just going to echo what a few others have already said here – few options for larger sizes, quality is sketchy, and they’re overpriced for what you get. The wires have poked through all my VS bras within a few weeks of getting them home. And, contrary to what some guys & some VS marketers may think, there is such a thing as too much lift. My current fav is from a department store, and it has no tags – the label stuff is printed on the band itself. I hate tags!
I love it. I’ve bought many cute shoes, comfortable thongs, sexy swimsuits and well-fitting bras there. I love their mix n match swim suit section.
I agree with the “made for a certain shape boob” comments. I tried on every bra style in my size (and even some in a different size) at VS at one point, and NONE of them fit my boob shape–and that’s when they were newly perky (after my reduction) and a perfect size! (Technically, at one point Hallgirl 1 and I wore the same size–she buys all her bras at VS and they fit fine, but the same size at VS wouldn’t fit me at all.) Plus, they’re expensive!