OK here are mine.
1. How come when you are a "soul" you can get physically sick like rukia's sister and Ukitake? Ukitake coughed up blood in an ep. that means one of two things Tuberculosis or Lung Cancer... how can a soul get those? Never really got that.
2. In one of the early episodes when they first got to the SS chad ran into that parakeet kid and the kid told him when you go to the soul society you don't grow or change but rukia and renji and other did grow up...
3. In the SS there were markets that rukia, renji and their friends stole from. Why have market at all when most souls don't eat anything? and how was there rice and fruit there?
4. How dose a soul die? and where dose it go after that? eg. rukia's sister.
5.
6.
I agree with a lot of stuff WONDERMIKE brought up except one thing. Renji's bankai.
It is just as big and cumbersome as Komamura Sajin's bankai, and he uses it well, some are just huge and I think it fits him. The fact that it can now spread into sections is part of its development. It will probably have a few more features as renji masters it.
Same with ichigo, I can't believe its just speed he has. I think he will develop it further.
As for what Jays said about ichigo's lack of development of his character well...
#1 he is only 15
#2 Its manga the character needs stuff to always be working on when it comes to character.
#3 Without that hardheadedness he would not get into trouble and there would be no story.
#4 He will always care for his friends more than himself because its manga...