Andrew Cristi and Jonny Lee Jr were memorable, but the entire ensemble was fine. My only issue was with the "Please Hello" number, where the lyrics were often incomprehensible. Given the quality of the rest of the performances, I suspect this was a sound design issue. This was the first preview that I attended, so hopefully that can be addressed.
I've only seen one other production of this show - Signature's earlier version in 2005 - so my memory didn't notice any specific script changes. I do know that I left the theatre much more satisfied this time.