Public discussions of life extension suffer from the confusion between two possible meanings of it.

The first meaning is to just postpone death. Maybe at 90 you don't remember anything any more, the list of your chronic diseases doesn't fit on a page, you require round-the-clock care and semi-permanent sedation, take 37 different pills and need a trip to the hospital weekly -- but by golly! we can and will keep you alive for ten years more and as medicine progresses we'll keep you alive for twenty years more.

The second meaning is to postpone senescence. You're 90, but you look like a 60-year-old. You're mobile, active, with most of your mind intact, with a functioning immune system and ability to enjoy life.

I feel these scenarios are rather different. In particular, they lead to different answers to questions about whether life extension is worth it.