I most liked that just before his death Roy crafted some poetry.
Creating Art? Isn't that what it means to be human?
Because, frankly, he may as well try not to kill Deckart, at all. For empathy. Or ask Deckart about how does he do, instead of going into monologue.
I interpret the ending as Batty coming to the end of his life and realising that all life is precious, not just his own. That's why he saves Deckard after toying with him and then goes into his final monologue that taunts Deckard with how much more of a human life that Batty has experienced.
Of course, there's all the Christ symbolism with Batty's "crucified" hand and how he saves Deckard despite him killing all his friends and intending to kill him as well.
The voiceover in the original theatrical version makes this very explicit, in fact.