I’ve been running Android P on my Pixel 2 for a couple of weeks and I have not had any problems with it. I also think it is an iterative improvement on Oreo, meaning that if you don’t have It you aren’t necessarily missing out.
Android Police has a complete rundown of all the new things. Oddly, my favorite may be the charging sound, as I have had cases when I thought I was charging my phone when I wasn’t because the charger was completely plugged in. The cleaned up settings and notifications are nice, and the navigation improvements are ok but not amazing. I am still looking for significant improvement in battery life.