I spent a bit of time playing with the Pre Plus at a Verizon store, and while the OS seems very nice, the hardware left some things to be desired and the app ecosystem is really suffering.
The keyboard simply wasn't that great - even the Droid's is better. The screen is too small and is made of plastic, not glass, so it simply isn't as smooth as the Droid's or others. And while I can't say first hand, I've read the battery life is very poor, again making the Droid's look good.
If you can live with the smaller app selection, keyboard and screen, there's no denying the webOS has potential. But whether or not Palm can capitalize on it is something else entirely. As for Android, new phones keep coming out on virtually all carriers. The downside to all that is hardware & OS frangmentation. WinMo eventually collapsed because its frangmentation went unchecked for too long (well that and the OS sucked to begin with!).