I actually would agree with Bingowings recommendation to start at the Eleventh Hour. It will help you catch up faster and introduce you to the current Doctor.
On a side note, I watched "The Girl Who Waited" and absolutely loved it. In my opinion, it has been the Sixth Season's best episode so far; it also didn't necessarily feel like a Doctor-lite episode. I thought the make-up effects were great and it had a deep story line. It emphasized the time travel aspect of Doctor Who without feeling like it was trying too hard.
This is one of those episodes that really shows the acting skill of all of the main characters, and it was absolutely lovely. We finally get some long-awaited character development and tension. Seeing the Doctor's more manipulative and darker side was good, as it had been absent for awhile and Matt Smith knows how to portray it well. There isn't an episode in recent memory that had such an emotional ending without being corny.
An aspect of the episode I reveled in was the use of the Eleventh Doctor's theme; it happened loads of times during Series 5 but was generally absent from Series 6. While I do acknowledge it as a gimmick much like the Indiana Jones theme, it is effective. Series 6 on the whole has felt like it tries to be convoluted and this was a nice blend of straight adventure and deep sci-fi.
