One of the best shows I've seen in a long time. One word - tension. These guys, formerly behind 24, know how to build it. Combine that with actors like Claire Danes, Mandy Patinkin and Damien Lewis and combine paranoia and psychological issues with the constant war on terror and "Any means necessary" attitude, and it's pretty much a wrap. I tried to find a subbed version of the Israeli show it's based on, Hatufim, but no such luck.
Just got continued for Season 2, although I hope it won't overstay its welcome. Six seasons and a movie. 10/10 and recommend to all.