I have not used the stick myself, but as someone who has extensive experience with the Happ / IL catalogue of parts I can tell you that the buttons are not going to be very sensitive compared to Sanwa or Seimitsu parts. They use big 'ol cherry switches like you find in a joystick, so they have a farther activation and reset distance meaning you have to press harder and deeper (yes, I know that’s what she said) than you do with Japanese sticks, unless you mod them. Also, they are convex which is not a very popular design for fighting games.
IL does make a nice drop-in replacement called “competition butons,” which have a convex surface, which means a larger surface and easier activation.
Unfortunately, the stock switch is still a cherry switch, which still has the sensitivity problem. There are replacement switches you can buy that have better sensitivity that work on both the MK stick’s stock buttons and the IL competition buttons that make them more sensitive, like how Japanese buttons are. Groovy Game Gear makes ones called “micro-leafs,” which I used on my last Happ stick project.
Micro-Leaf Arcade Pushbutton Switches [MICROLEAF001] - $2.49 : GroovyGameGear.com, Always the best in Arcade, Jukebox, Kiosk, Gaming and Industrial controls
It looks like a solid stick for MK fans overall, but I would definitely want to replace the parts with a proper IL Competition joystick and pushbuttons if I was going to use it.