Spoilers sprinkled below :D
I am no 'technical' reviewer and i don't do research about their graphics or director. I am writing my reviews based on my feelings after watching them and without being overly biased.
First of all, it's certainly worth watching (for the first time that is) but
Honestly I did not enjoy both series as much as I think I would. The fighting scenes were ok in a way but then they decided to skip the final climatic duel between archer and saber. The only good ones were probably between lancer/saber and between kirei/kiritsugu The story involves too many ineffective twists where people just die from psychopathic homocides/chokes. The conclusion/final episode was especially weak for me and I was confused for most of the time. To me it wasn't properly addressed and everything was just smudged to an end.
The opening was fantastic, it sets the perfect atmosphere.
It would have been better if an alternative ending was used instead. The ending really pulled the whole anime down. You don't simply put people from one scene to another without explaining or hinting it simply because it was magic.
This is one of the where no good things happen anime. Everyone's dream was destroyed to some extent and suddenly the anime ends (at least that's what i feel) leaving me as a viewer dissatisfied.
I have not read the manga or seen fate/night so these two seasons are the only things i base my review on.