Pretty good series
I initially began watching this last year but abruptly stopped at the second (or third?) episode. I [daftly] decided that the confusion of trying to keep the Kiritsugu/Tokiomi/Kirei stories straight was too much and it became more of a chore for me to watch.
Months later, I revisited Fate/Zero, and after the fifth (I think) episode, I was hooked. I found myself really enjoying the premise, the characters (including some of their legendary/historical components), and the action. After every episode, I only wanted more. Not saying that all questions you may have will be answered, but it's definitely enjoyable and entertaining--and some parts do tug at the heartstrings.
I'd never seen Fate/stay night so I have actually started watching that.
Mr. Rusk...you're not wearing your tie!