The SETI implications
The good news: M dwarfs are so numerous, and so long-lived and generally stable, they are good places to look for planets. Being relative lightweight stars, planets would be easy to detect there with our current methods.
The bad news: M dwarfs have very narrow habitable zones, and planets lying in them would be tidally locked, so one face would always be turned to the star. How this might affect planetary weather is not well understood. These stars are also highly prone to flares, so planets around them would need to have a mechanism to replenish their atmospheres and life on the sunny side would have to go underground to escape the radiation.