Personally, I haven't flown on either since the early 80's when rode Northwest a few times. My family is a United family now, and will probably stay that way. Although I did take a trip on JetBlue last year, and really enjoyed the experience.
Not much more to blog on regarding this merger. It's just been announced, and the pundits haven't had much of a chance to tear the idea to pieces. No doubt there will be the usual winging about reduced options and monopolies... blah blah blah.
Read the official announcement HERE.