I have the Speck Smartshell in clear on my 13" rMBP. It's thin and snug, and doesn't add any appreciable bulk to the laptop. I also like the clear design because it preserves the look of the MBP. I carry the laptop around my house quite a bit and value the protection again scratches and bumps that might cause a dent or unsightly ware and tear. When I leave the house with it, I slip it into a padded compartment in my backpack, so the hard shell works out ideally for my use.