Re: Was I the only one shocked during the big reveal?
The film definitely needed to use Talia al Ghul because it brings back the League of Shadows, which is necessary, imo(and especially if Nolan wanted to end Bruce Wayne's story arc...the best way to do it is bring back what helped his version of Bruce even become Batman), but Talia needed a bit more development. If the third act was longer, Talia could have still made her reveal then if she was given more time.
I do like BatLobster's assessment with Talia though...she was more of an idea than a character. As much as Bruce had a new mindset of starting his life over, Talia had the mindset of just destroying a city filled with demons while Bruce was trying to walk away from his own past demons, but he still needed to save it before he could leave.