Confusingly it's both obvious and unpredictable. There are various tropes, which you can see coming from a great distance, and give the show a cheesy feel among all the violence and scheming. It's obvious who's going to murder who and who's going to be a really crappy husband. It's clear which character is particularly significant, we don't need a ghostly dream prophecy to tell us, but we get one anyway.
|A present from my mother-in-law|
The only reason I know part of the outcome is history. Medieval history is not my strong-area, so I consulted my History Mug.* As you can see it told me that there is no King Eustace. In fact a fist-shaking King Stephen is succeeded by a lively young Henry II, who apparently enjoys leapfrogging small tables.
I've never read the book, so I don't know how faithful the miniseries is to the source material. Though wikipedia informs me that the incest and suspected witchcraft were added in for television, because who doesn't love watching that? I have vaguely considered reading the book, but there are so many other books to read, and then they put it on TV for me anyway. A similar thing happened with Lord of the Rings.
I thought the setting seemed pretty good. Medieval England is skillfully played by rural Austria and Hungary. There's plenty of dirt and muck, which is what history was like, although certain main characters (especially women) still look a little too clean and glamorous.
* Ok, so it's actually a Kings and Queens of England since 1066 Mug, but that is not as catchy.