The lower case is secured by a few captive Torx screws. Torx isn't as common as Phillips, but should better withstand repeated removal. Captive screws will also be hard to lose.
The case is fairly well secured and requires a thin plastic prying tool to gain access; fingernails won't be strong enough and metal tools will likely scratch the laptop surface.
The bottom case contains no major components, making for easy replacement, and the laptop itself has a flat construction that allows access to most components at this stage.