I got my HP touchpad for $100 during the fire sale and have not used my android tablet since.
In terms of the UI and the keyboard, webos easily crushed any other mobile OS, the only limitation is the number of apps.
it offers far better multitasking than android or iOS, extremely easy to mod.
For the most part, I am hooked on webOS mainly for the multitasking (gestures instead of a screen space wasting home bar thing)
and the keyboard. I don;t think anyone could possible find the android keyboard or iOS keyboard better than this. it actually has a number row that you don't have to go through a menu and
Here is a screenshot from my HP touchpad that I am using right now while in bed
http://i.imgur.com/Tln80.png
The tablet also performs extremely well, especially when overclocked to 1.89GHz, and also when the GPU is overclocked from 266MHz, to 320MHz (faster than tegra 2 at stock speeds) (with room for an even higher GPU overclock)
it currently has a relatively stable CM9 build with CM10 jelly bean in a very early alpha stage
It just runs great, and can handle 1080p videos smoothly.
With this tablet, HP got a lot right, where they failed was charging ipad prices at a time when their OS hardly had any apps. when it first came out, it was priced to compete with the ipad but it had only a hand full of applications (all the rest in their claims were from older webos devices that it was able to run in a emulation mode that was poorly made since it only uses about 1/4th of the screen to display the app in a tiny window and fill the rest of the screen with a gray gradient. (at least android allows you to expand the app to fill the screen and if it is made right, text and other things will scale well.)
anyway, the device only had a bad start, other than that, it is still one of the best tablets on the market.