What I found most intriguing is that in the movie, Dave is fast forwarded and reborn whereas in the book, he is rewound, uploaded, then chooses his form by his own free will. The movie version is spiritual while the book is humanistic.
I can see where you are coming from, but it's also conceivable that movie version also follows the book version - just we're not privvy to Dave's thoughts. (Special effects at the time were just not up to doing the raging surface of a sun though...)
I think the problem I have with adaptions is that because film and prose are different mediums with different tempos, requirements and issues it's difficult to translate effectively between the two.
Generally IMHO most film adaptions were worse than the novel/short that they came from (and vice versa most film novelisations are pretty dire.)
There are exceptions. I too would rate LotR as an excellent adaption of an unadaptable good book (I should keep stumm on this, as I'm sure there are plenty of people who vehmently disagree with this view on this site
).
I can't remember the book of The Shining, but the film is utterly brilliant - watch it in the dark by your self with that really evil soundtrack cranked up loud, brings shivers to your spine. (I do know that Stephen King didn't like Kubricks film, WTF ?!?!?!)
And I'm also going to stick my neck out and say that Total Recall was a good attempt on, again, an unfilmable short story. A different spin, yes, but the cartoon violence is justified if it is all a memory implant!