First of all, I must say that I rewatched FSN this week before seeing this episode, and I have to admit, I kinda ruined the rest of Zero for myself...in a way. I was totally surprised at how much I had forgotten about FSN and how much they refer back to the previous holy grail war. In saying this, I think because I had forgotten so much, F/Z was much more entertaining than it should have been. Not to say it's bad, not by any means. But now I kinda wish I would have held off like I originally planned to.
Anyway, now that I am refreshed on whats going on, 12 was a good setup episode. No action, but it set up well the future alliance between Kirei and Gil. I must admit, I actually like Kirei a lot here because it showed how much he struggled to stay true to himself before becoming the eventual ass that he is in FSN. I am glad, however, that they confirmed that Assassin is completely wiped out this time. I really didn't want to go another episode where all the servants live again...
Judging by the audio preview, it looks like next week things will pick up again. I really want to see some actual fights this time (last week's slaughter didn't count in my book). Especially if Gil, Rider, or Berserker are involved.