I've got two! I love how chonky the pen is. It writes quite well out of the box. It just felt a bit dry for me, but I love wet pens so that's probably a me thing. I just tuned the nib to write wetter.
People say it's a copy of the MB 149. I've never tried a Montblanc, since it's out of my price range, but I'm quite glad to have a cheaper alternative because the thickness of the Jinhao x159 is perfect for my death grip haha.