so many of you have said that she should buy it because it was on SATC.  That's exactly why I would never wear it!  A look as iconic as that stands out.  Just look how many of you saw SJP wearing it!  
I think you'll look like you don't have any style of your own and are just trying to copy someone elses.  I think it would be much better to find a dress that has the same feel, but is even BETTER than SJP's.  It is possible, you know.  And then you'll be making a statement of your own.
ps-the reason someone thought it looked retro is that it's a very good interpretation of a Givenchy dress Audrey Hepburn wore in Bkfst @ Tiffany.
It's a beautiful dress, I would just feel like I was wearing someone elses clothes.