b) They didnt wimp out with the ending...the nukes actually flew.
The only problem with that is that it flies in the face of the second movie, where Judgement Day was a possible future, not the future, set in stone. There is even an alternate ending with Sarah Connor in the future seeing kids (her grandchildren?) playing in the park that got destroyed in her dream, indicating that they had stopped JD.
In the third movie, the future is immutable, you can't change it, one way or the other, which in my opinion is weaker from a story telling point of view.
That's not to say it's not an enjoyable silly movie, but it's far from the heavy hitter and absolute classic the second is (which in my opinion, is a greater movie than the first one as well).