If it's one store the US doesn't have it's a Jacob store. And for those looking for the basics and classics, this is the store to go to. That said, like many stores recently I feel like the quality has dropped.
VIBE
This location in particular is pretty stark white. Their front section is good. If you go downstairs, it's where you'll find lingerie and sale items in addition to sportier wear and more changing rooms.
Staff are pretty hands off but friendly.
THE GOODS
Their front section is usually where the best stuff is. I find better stuff on the upper floor than bottom.
I quite like the Eaton Centre location (didn't see a listing for them). They renovated a year or two ago and their lingerie section is quite good (lower level). I've also picked up some nifty costume jewelry from them.
If you're looking for work gear, this is the place to come. I especially like Jacob for its shirts. Affordable coats/jackets are also good buys here.
OBLIGATORY CATCHY REMARK
it's quite refreshing to say we have something that the US doesn't. Na na na na!
Note: the Yorkdale and Eaton Centre locations are quite good.
The First Canadian Place location has some pretty good sale items if you can get down there during the day.