Here are different elements that you could consider as pros, cons, and sometimes in the middle, depending on the photography you do, concerning mirrorless cameras.

• Smaller and lighter: Thanks to the absence of a mirror (used to project the light coming from the lens through the optical viewfinder on DSLRs), the distance between the sensor and the lens is narrower, resulting in smaller and lighter bodies. Furthermore, as the lenses are closer to the sensor, they can have a smaller diameter, resulting in smaller and lighter lenses too! Nevertheless, in some cases, having a big camera can be useful. For example, when doing long exposure photography, it's nice to have a sturdy setup. Else, having a bigger camera can look more professional and this can be seen as an advantage for some photographers. Furthermore, the grip is usually better on bigger cameras.

• Smaller battery life: This is definitively a con. As the light is actually captured by the sensor and recomputed in order to be displayed on the screen (or the electronic view finder), the battery lasts less longer than DSLRs. Furthermore, as the bodies are generally smaller, the batteries are also smaller resulting in much shorter battery life.

• Focus: As the focus is computed directly with the sensor, it should be more precise. However, it is usually slower than DSLRs focus system.

• Lenses choice: The big DSLR brands (like Nikon or Canon) have a huge range of prime and zooms lenses, while mirrorless cameras usually have less choice. However, this will probably equilibrate in the future as mirrorless cameras are becoming more and more popular

I've been using a DSLR for years and I'm now about to switch