The Guardian released NSA's papers on TOR:
http://www.theguardian.com/world/interactive/2013/oct/04/egotistical-giraffe-nsa-tor-document
http://www.theguardian.com/world/interactive/2013/oct/04/tor-high-secure-internet-anonymity
http://www.theguardian.com/world/interactive/2013/oct/04/tor-stinks-nsa-presentation-document
They are pretty interesting and I recommend everyone to take a look at them.
And like always: please use TOR whenever possible! It makes the whole network even more secure.