A bit of a disappointment to me
*spoilers... but not really*
Sorry to rain on everyone's eulogies but as much as I can understand why it is a miracle that this managed to come out in Spain in '63, I think the story, although original, is a bit dull and the ending falls flat. I wasn't expecting a typical 21st century Hollywood twist either but I've seen much better films from the 60's from various countries. This is probably a very important film for political reasons but I don't really think it stands the test of time. It is still watchable and sometimes captivating but nothing unpredictable ever happens !
One I enjoyed much more about the death penalty (although a tad bit more recent) was Lelouch's "La Vie, L'Amour, La Mort" (http://www.imdb.com/title/tt0065179). Different in every way, but more worthwhile in my eyes if you have an interest in the subject.