New to the HP Slate forums, but not to Android. I have several other Android tablets.
The most recent addition to the family is an HP Slate Plus 4200 model. My local MicroCenter outlet had refurb 4200 units on sale for $50, and one came home with me.
The selling points were the 5MP rear facing camera and the Tegra powered 1280x800 screen. Essentially, I got a digital camera that happenes to be an Android tablet for $50.
The main drawback was Android 4.2.2 Jellybean, when Marshmallow is current, and Nougat is rolling out. That's not a deal breaker here, and very little I have elsewhere fails to run under Jellybean. (The two that don't work offhand are the Termux terminal emulator and the Taskbar start menu, which require 4.4 KitKat or better. I can live without them.)
The device was simple to root: Kingo Root from Windows connected via USB cable did it on the first try.
I did have to exchange the one I got - it suddenly decided it didn't see a microUSB port. It wouldn't charge, recognize an external USB keyboard, or connect to the desktop via USB. When I powered it off, it would not power on again. A replacement is plugged in and charging as I type.
Poking around elsewhere reveals a custom ROM for the Slate offered on XDA Developers. That's of interest but I'm proceeding with caution.
Most of the bundled software is likely to go away, and preference is given to open source in what I install. There are good open source packages available from the F-Droid repository for most of my needs.
Looking forward to talking to other Slate owners.