Could be stuff considered minor spoilers in here; don't read unless you don't care or you've finished the show.
I rate too easily to begin with; theres no way I can give shana any rating other than 10/10.
The entire season was great for me, when Yuji showed up in the first episode as the leader of Bal Masque with the Snake of the Festival I was freaking out with excitment for a few days after. Yuji looked amazing, and he had an ideal that would change the world.
The season had a great balance of action and slow-parts where not much happened. The final episodes are action-packed and beautiful; they portray the desparity of both Yuji and Shana in their attempts to succeed with their respective goals.
To conclude, The final episode is simply indescribable for me. I couldn't think of anything to say while watching in awe of the series conclusion. I'm supremely satisfied with the ending, probobly to the point that I'm emotionally moved by it; something that only Zero no Tsukaima's First and Second seasons were able to do to me when I first started watching anime my freshmen year of highschool four years ago.
As a review is somewhat meant to be a personal opinion, this is what I believe. The years just begun; but Shana was definetly the Greatest ending of 2012.