The pilot episode,
I thought it odd that Hawaii 5-0 would open with a scene in South Korea. It's like stumbling out of bed in the morning not exactly sure what you're going to do that day.
There are also seemed to be to much gun play and not enough acting. The dialog and some of the background setup (Danno's family situation, for example) was a bit too clichรฉ. Some of the personal background could be better developed over time rather than cramming it into one episode while chasing the bad guys.
The overall storyline for the pilot was excellent, though. It gave background to 5-0's beginnings and it maintained a certain consistency and plausibility with TOS while adding the dimension of McGarrett and his father.
Some of the dialog resulted in an approving chuckle from me.
The episode began to gel about 2/3 in and by the end of the show, I felt comfortable with the main characters and looked forward to the next chapter.