If you already have a pen tablet (a screenless tablet) and are considering getting a pen display (a screen tablet). There are a few considerations you should take into account.
You should carefully evaluate what these advantages are before you switch. More here: pen tablets vs pen displays.
One thing that I often hear is that people find that it feels weird or strange to draw on a pen tablet like their hand isn't drawing what they expect it to draw.
Many times what I found is that people have not configured their pen tablet correctly for their monitor's aspect ratio. More here: matching aspect ratios.
So if your tablet is feeling weird, try matching the aspect ratios and give it a few more days. You might find that after this change you enjoy using your pen tablet much more.