The "Slim" part of its name is handily apparent, as Computer Shopper reports it's the "thinnest of any drive at the 2TB capacity," with its thickness not even topping a half inch. The Wirecutter says it's even "thinner than my smartphone in an Otterbox case." It's not quite as tough, as StorageReview notes "the covers flex inward until they touch the drive inside if you grip it with your fingers hard enough." However, Computer Shopper found it scratch-resistant, and The Wirecutter says it's still "very sturdy" and "should hold up to normal bag friction."
You'll definitely want to throw this in your bag and take it to the office, or on your next vacation to back up photos -- while it doesn't blow larger drives out of the water in terms of performance, StorageReview thinks it "will get the job done for most mainstream users" with the upshot of a "skinny form factor."
The Backup Plus Slim might top other drives in the speed department, but it's fast enough to get the job done and small enough to go anywhere. And, with its low price, you're getting far more than your money's worth -- you might as well buy two.