The device is protected with extra seals to prevent failures caused by dust, raindrops, and water splashes.
We consider a lower weight better because lighter devices are more comfortable to carry. A lower weight is also an advantage for home appliances, as it makes transportation easier, and for many other types of products.
The device is dustproof and water-resistant. Water-resistant devices can resist the penetration of water, such as powerful water jets, but not being submerged into water.
An optical viewfinder (or OVF) allows the photographer to compose a shot while seeing exactly what the lens will capture. OVFs have no time lag and require no power - as opposed to electronic viewfinders, which can drain battery life. OVFs are also better in low light situations.
A hot shoe can be used to attach an external flash, as well as light meters, viewfinders, rangefinders and other attachments.
A higher screen resolution provides a sharper image, making it easier to review your photos.