As far as Sakura goes, she irritates me with her personality....in part I it was the Sasuke obsession and rather mean treatment of Naruto. Then in part II she becomes indecisive. She says I'll tell Naruto. Instead she pulls a cockblock (probably the worst thing she has done). Then she screws over the people trying to help her. Finally she cent pull the trigger so to speak. She freezes at the last moment.....but honestly she has shown parts to her that are awesome......I wish we had gotten more of the Sakura that fought Chiyo....now that was a Sakura I respect! The only other thing is that she is a Tsunade clone, bit she didn't do anything advanced or unique with it like Naruto and Sasuke did....she supposedly has talent in genjutsu, but never used it....that was dissapointing!
In terms of ability, Sakura isn't exactly a Tsunade clone, she's more apt with bukijutsu than Tsunade is and Tsunade uses the Kuchiyose, with generally speaking Sakura doesn't. She's skilled at recognizing and dispelling genjutsu, not at casting them (which once again is something Tsunade can do instead). Sakura also has scenes about analysis and enigmas, like the one in the anime Shino had (where Shino outwits several Zetsu clones trying to make him and Kiba kill each other) where she shows that what she doesn't have in raw power, she makes up with strategy and analysis. Overall she's not as mighty as Tsunade, not skilled with tools like Tenten, and not a good planner as Shikamaru or Shino would be, but I'd say she's far from incompetent.
About her personality, I think that Kishi did a good job. Sakura started as immature and egocentric (Sasukecentric?) and that's something I appreciate. I dislike female characters to be saint princesses which they often are in Shounen since Saori Kido's old days. Sakura has flaws, downfalls and sometimes does just plain wrong things just like everyone in everyday's life. What's truly appreciable about her is not that she's a concentrated mass of goodness like Orihime Inoue (Bleach) but rather that she manages to grow up and overcome her flaws.
I'd say that's one of the good things he did with Sakura, not the wrong ones.
I also liked her move at the Land of Iron. One of the most irritating things is how people say she doesn't care about Naruto after that huge proof of the contrary. She was pratically willing to give
her body and soul to a man she sees only as a friend, to make up for the sufferings and burden he carries (which she feels to be the main cause). About Sasuke, she inverts the anti-feminist trope of the girl in love who can't help but be victim of the cruel man she loves (that is played by Karin) by deciding to save Sasuke by killing him. Both these choices show how strong she is and how deep is her genuine love for Naruto and Sasuke both. Kishi promised that Sakura would have her moment and I'm happy that she did. I can't see why people dislike her for these moves.
What really bugs me is that at that point, instead of playing an interesting Sasuke vs Sakura match, Kishi just made her stop at the last moment and took another chance to show us Sakura in this frail, human way. It's not a wrong move per-se but I think a different course would've been more interesting and maybe more natural.
That said, I think Sakura is overall a well done character.