I'm a fan of the general Guess style and while I enjoy shopping at all their locations I do enjoy shopping at this particular store because the staff have always been fabulous, not getting in my way if I'm just browsing or being super helpful if I need them. But their store at Yonge and Dundas is as great with perhaps a better inventory.
I agree with Lauren in that it is less busy than the Yonge and Dundas store which I prefer, and I have no real problem with them having a smaller inventory than the other downtown store. I wouldn't say that it offers anything extraordinary that is not seen in other stores, they have a sale section that can see you grab some nifty swag for the $20 price range, and most of their newer styles will cost you closer to a $100 (I'm talking about the guy options here), but I've always been happy with my Guess purchases. It is the friendly staff that make me enjoy walking in here so if you're strolling around Queen St W, it wouldn't hurt for you to pop in to this store.