I think it depends on too many variables to advise without more knowledge of your house/family/interior design/expectations.
We have a mezzanine landing (double height), as do my parents (triple height). It works fine in both houses because acoustics are not normally a consideration in halls/landings. Ours is quieter, probably a combination of double not triple and carpet not tiles/wood.
If your mezzanine lounge is going to go over a carpeted, curtained, wood table, plushly furnished dining space, and be see for quiet sitting/reading/knitting, then the two spaces will probably work together. If your rooms are tiles/wood, with lots of windows, a glass dining table and you want to watch telly/play games consoles in the lounge, then it will be a disaster!
Of course, if you're a two person household and you're only likely to use one room at a time then there'll be no conflict :)
Not much help, but hopefully given some things to think about ....