The first and foremost is that your skin will be less irritated as a result of the shave. Nearly everyone who makes the transition to safety shaving from regular cartridge razors comments on this.
A lot more customization options - you can mix and match a range of blades, shaving soaps, pre and post creams to form a combination that best works for you and your skin. Blades, in particular, come in a wide variety of sharpness levels allowing you to choose just the right sharpness: smooth ratio for your best shave.
Care of Harlife.