You know that highly complimentary saying "I hate to see her leave but I love to watch her go?" Well this small yet eye-popping detail gives these exposed back zipper sweaters a nice element of "wow" when exiting. They will love to "watch you go!" The exposed zipper is one of my favorite looks with sweaters. I like to wear them backwards sometimes (with the zipper running up the front) if the sweater is the right fit.
While the contrast in colors is a nice look - it can be easy to get limited with your styling options. I would only wear grey or pink to match the contrasting pink of the grey sweater. Just something to keep in mind. I also like exposed back zipper sweaters in solid colors, no contrast around the zipper like Ann Taylor's. They offer a bit more styling versatility.
However, the combination of the contrast in colors plus the exposed back zipper is pretty sassy and stylish. J Crew has some great colors like this cobalt blue exposed back zipper sweater and this italian cashmere sweater that comes in several colors.
If you purchase a good, quality blend, this is one of those pieces that has timeless appeal. I love a great investment!