Adobe flash player

Well, safe is all a relative term. As far as doing any actual harm to your system, Flash will not cause any problems, but it will eat up your battery life and hog your CPU, which some consider harmful. To control this you can install Click2Flash and then only view Flash when you want to.

Cheers!

Safe in what respect? What is it you are trying to avoid?

From my point of view, it is no different than any other application by which you intend to use your computer. Is it harmful? No. Does it cause a more rapid use of battery power? Yes, it is well know that Flash has a tendency to cause the computer to deplete the battery, faster.