Machines fall flat in many aspects: They don't heal, reproduce or "survive" well without human help in any way. Then again, they do things that are impossible with organic systems, like going to space, travelling at supersonic speeds or lifting hundreds of tonnes in one go. That's why technology has always been an extension of ourselves, but now we're taking the first steps to bring these different lines together. That will of course lead to some awkward in-betweens, which nature has produced as well (see the tully monster for example).