Romance for the Senses is a beautiful lingerie store in a great location in Old Town. They have really high-end products (Le Mystere, Belabumbum, etc.). While the prices are generally pretty high, they're what you would expect for really high-quality lingerie. Plus, they often have really great sales. I once got a pair of $60 panties for just $5! I've also seen $100+ bathing suits for $30.
The only downside is their really young, inexperienced staff. Perhaps it was just the day I was there, but once I was looking for a strapless bra and the girl (she must have been in high school) wasn't able to help fit me with the proper size. She recommended a size that was WAY off the size I am actually supposed to wear (see my review for Trousseau in Vienna for my bra-fitting story!). I ended up paying top dollar for a bra that isn't quite the right size, though I can still get away with wearing it occassionally.
Overall, great place if you already know your size and don't need a lot of personal, boutique attention.