I have this on a regular basis, especially when I'm extremely tired, laying on my back, when I wake up and take some time to fall asleep again or when my sleeping schedule is fucked. Never see any creatures, just paralysis and I'm always in a position where I have difficulty breathing (faced down on my pillow etc.). Always a huge relief when I wake up. My girlfriend recognizes when I have it because my body starts twitching and wakes me up if she notices.
Learned to not panic too much when I have it though, what helps me wake up faster is trying really hard to get some movement going most of the time in my fingers. Sometimes its a few minutes (or atleast feels like it), sometimes I wake up in seconds.
Never gotten used to it, I'm always fully aware that I'm going to wake up but when it takes a while I start questioning if there's something wrong with me and if there is I could be laying there for hours without anyone noticing.
Edit: the first time I had it was 6-7 years ago, I remember because it was during the morning and I had my window open and curtains closed. The wind blew against my curtains causing it to create some shape/pattern on the wall. I could see the shape during my sleep paralysis eventhough I'd never seen it before, when I woke up it was still there. Freaked me out.