Theres a huge difference once you use it for long enough. I have a 144hz monitor and love getting to play games that high, they’re so smooth! If you play long enough the difference becomes night/day.

Lucky you. Seriously. I wish I didn't care because it means displays are more expensive for me.

I definitely thought it was all hype but once I saw games 120+ fps, even 60fps looks choppy to me. I also very much notice the difference between 30fps and 60fps video but 120fps (at full speed) didn't do much for me

For what it's worth, I was a professional video editor for years so I'm a bit more inclined to notice than the average person

There are diminishing returns but I can absolutely tell the difference between my 165Hz display and my wife's 240Hz.

It's very easy to tell the difference when you see them in person. I have a 60Hz monitor and a 144Hz monitor on the same PC and you can drag a window across the desktop from one to the other and the lack of animation frames in the movement going from 144 to 60 makes the movement look choppy on the slower one. In games, the animation becomes smooth to the point of being lifelike and visually vibrant when your framerate is able to go up to 90 to 100 or more FPS

It really depends on what and how you play. If reaction time is important then you'll feel more than see the difference in refresh rates. If none of your games require sub second reaction time accuracy, then it's much more of a nice to have luxury than a game changer.

Also, frametime pacing matters a lot. If your system very consistently puts out 30 fps, you'll have more accurate keypresses than if you normally get 50 and it gets hung on a few frames and it dips to 30fps. Your nervous system adapts pretty well to consistent delay, but it's much more difficult to compensate for delay that varies a lot.

I don't really play first person shooters so resolution matters more to me than framerate.

For 3d games where the whole screen is moving and changing as the camera moves, I've noticed a big difference between 60 and 144. It just makes the game feel absurdly smooth.

For smaller games with more static views it doesn't really make much difference.

It mostly depends on the speed of the game.

Here's a site which nicely demonstrates the effect: https://www.testufo.com/

Occasionally my fps gets set to 60. As soon as I start playing rocket league I can tell it is off. I went to a friends house and asked why everything is so choppy, checked his monitor settings and it was set to 60 instead of 144. There are people that can see the difference

I can tell you I notice no difference between 240 and 60

Stability is all that really matters