Okay, first off, I would like to mention that this is not, in fact, a Sakura hate thread. If I wanted to hate on Sakura, I would have just commented about it. Second, I'm going to hold back from just calling her weak without hard facts to back it up. Third, READ THE THREAD! No commenting before posting, or expect to be flamed!
First off, while they were fighting Zabuza and Haku (The very first enemies in the series!) while Naruto and Sasuke were doing ALL the work, what was Sakura doing? CRYING! That's what.
Fast forward to the Chunin Exams. "When Team 7 is entered into the Chūnin Exams, Sakura is reluctant to participate because she feels she is too weak." Straight from Narutopedia. Even Sakura knows when she can't beat anyone.
When Naruto and Sasuke were owned by Orochimaru, Sakura was left to take care of them. A couple of fodder genin took this opportunity to attack, and what did she do? WAIT FOR SOMEONE TO SAVE HER!
She's the main heroine, so of course Rock Lee comes to her aid and seeing as Rock Lee can't win a fight due to plot no jutsu, he is defeated. The fodders turn their attention to Sakura. She uses the most powerful technique she ever has so far, cutting her hair. Even though this does devastating damage, the fodders manage to continue after her. Then she performs a jutsu no normal human could possibly pull off, Bite no Jutsu! Another devastating blow to the fodders, and she comes in for the finishing attack, Wait to be saved no jutsu!
This finishes them off from the time being, while doing so much as seeing Sasugay in his Curse Mark triggers Sakura's Water Style: Cry no Jutsu!
When Sakura fought Ino, her Mind Transfer nearly costed Sakura the match, but since Naruto saved her with Talk no Jutsu, she managed to pull off a tie.
When Sakura faces Gaara, she gets finished in 5 seconds flat with one technique. She looked better sitting there staring at Sasuke crying. Which she subsequently did when Sasuke said he was leaving the village. Her Water Style wasn't powerful enough.
Sasori vs. Sakura and Chiyo. Ironically, she looks best when she's being controlled like a puppet. Even with Chiyo's 11 puppets, Sasori still let them win. You can't do much crying when you're being forced to fight.
Before this gets too long, she has cried in nearly every major moment afterward and is Unable to beat anyone who is not a ninja, and even if they aren't very high difficulty.