Wow, I just woke up and found out how much comments are here since last night.
Again for Sakura fanboys/fangirls.
Sakura was useful in the Sasori battle, but with HELP with an experienced Grandma. So, Sasori had to fight against two, not one. Plus, if it was Sakura vs Sasori (ALONE), Sakura would DIE cause Chiyo was stating a lot things about Sasori to GET OUT OF HERE FOR A SEC and PREPARE YOURSELF. Without Chiyo, youre DEAD.
Tsunade couldn't defeat Kabuto (and surely Sakura too.) and one of Tsunades strongest punches didn't actually kill the person, but more likely severely injured that you are almost dead, but Sakura has less strength than Tsunade.
The question for your thread is how useful is Hinata.
Well, in the Pain Arc, Pain stabbed many rods on Naruto without killing him and that could been the end for Naruto to have get taken away and have his bijuu extracted until Hinata come and saves Naruto. She tries to break most of the rods, but Pain interfered with the Almighty Push. So, Hinata landed one punch on Pain with her Twin Lion Fists, so she can break the last poles. But at least Naruto got free when he saw Pain stabbed her. Without her, Naruto would be GONE... So, here is something useful. Plus, Sakura did state to herself that she had to save Naruto, meaning that she wasn't useful.
By the way, if Sakura was to fight Pain, Pain would demolish her. Kakashi had a difficult time fighting Pain, even with his sharigan to predict and fight Pain's moves. Sakura would have a hard time fighting and would fail in a sec.