I think it's going to be a fine line. We used to have one, and until it was abused it ticked along peacefully enough.
I suppose we'll see.
M
I've always been in two minds about a like button, but it has its uses. If someone wants to add comment then they can and it saves a lot of "+1" and "^ I agree" type nonsense posts that really don't add anything. Also it's handy for reviews and articles where it's nice for the writer to have some feedback even if the review isn't necessarily about anything the reader wants or is interested in but appreciates the effort put in and the good read.