The HP Touchpad was such a joy to use. WebOS was really smooth and significantly more responsive than Android tablets at the time.
One specific feature I miss is when switching apps, the app cards were live views of the app, rather than screenshots like in Android.
It took a decade for apple to bring synergy to iOS, and it was live when the touchpad launched and also simultaneously died :(
webOS multitasking, and gesture navigation were way ahead of their time.
After HP wound it down, the main guy behind WebOS, Matias Duarte went on to Android and then implemented Material Design there.