The zip continues all the way to the points of the collar to allow you to zip the collar up in particularly cold or windy conditions.
As the slit pockets are positioned in line with the seamlines of the jacket, it preserves the clean vertical lines of the coat
Only having a single button closure would not be ideal for cold and windy climates as it would not be effective at keeping the wind out - more fashion than functional
While the sale price is closer to what this question is asking for ($159.25), the regular price is quite a bit higher ($325).