I may be in the minority, but I think the original ending was good.
(Spoiler alert - don't read if you haven't seen the original series and plan to.)
Deb had to die because she never would have been at peace after Dexter put her in a no-win scenario, choosing between protecting him (by shooting the captain) vs. upholding the law. Dexter would also never be at peace knowing how many innocent people have inadvertently died because of him - especially his sister and his wife. However, rather than giving in to the hurricane and putting himself out of his misery, he probably felt like he didn't deserve to be at peace, so he faked his death, moved to a colder climate, and took on a job he didn't really want. It wasn't a happy ending, but I thought it was appropriate.
We haven't watched the new season yet (we don't get Showtime), but we'll get a trial sub and binge it soon.