I just ran into this while writing this question.
[I originally wrote:
you need a minimum of X reputation to comment on questions that are not your own, and on answers that are not to your own questions
But had to shorten it to:
you need a minimum of X reputation to comment]
First, it didn't tell me that I'd gone over the character limit for the title until after I had already tabbed out of the title field.
Second, it didn't tell me how much I'd gone over or anything. I had to copy-paste the text I'd written into my text editor in order to get some real-time feedback on the exact character count, to help figure out how to best shorten it.