It's been over a year since the iPad was first announced and in that year, its age is starting to show. The shine is off, the wrinkles are deepening and when you compare it spec for spec to the TouchPad and Xoom, it's no contest. Think about it, the TouchPad will have a 1.2 GHz dual-core processor with 1GB of ram. The Xoom? A dual core 1 GHz processor and 1GB of RAM. The iPad has a single core 1GHz processor with a wimpy 256MB RAM. Those are specs fit for the convalescent home. The TouchPad has a front facing camera. The Xoom has a front facing and back facing camera. The iPad? None. You get the idea.
The Pre may have failed but webOS was great. Not only is it a beautiful OS to look at, it's a great one to use. Its true multitasking is the main attraction and obviously works (well, with a limited number of cards open), but don't forget that because webOS apps are built using web standards, it scales wonderfully to different screen sizes too. That means webOS will be just as lovely on the bigger screen of the TouchPad. WebOS will never be mistaken as Speedy Gonzalez but I imagine it'll be able to utilize the extra tablet screen space a little better than iOS' rather elementary app launching homescreen.
Limitations of iOS are well known at this point: a terrible notification system, multitasking that doesn't feel like it's capable of doing more than one thing at once, the lack of Flash, etc., but it's still a pleasure to use in tablet form because hardware limitations or not, it's fast. There's little slowdown to ruin the experience. Responsiveness is perfect. And don't forget the billion or so apps designed specifically for the iPad.
The Xoom is the wild card here. On one hand, it feels just like what an Android tablet should feel like. Fast, responsive, customizable, widget-ed, and has the only OS designed strictly for tablets. But on the other hand, the weird Wi-Fi rumor is troubling and brings questions on if the carriers will find someway to ruin it.
Remember, the experience of using a tablet isn't as demanding as using a phone. As much as tablets are all the rage, people still view them as luxury items to be enjoyed, not something you use to get shit done. Biases that come from personal phone usage shouldn't really apply here. You're not going to use them the same.
They're all 10-inch slates, so they all have a similar core design: a big screen and a thinnish body. The iPad gets bonus points for using better materials. The TouchPad gets docked off a bit for using all plastic. The Xoom is right in the middle.
But really, a tablet's design is probably the least important aspect (certainly less important than a phone's design, for example). A successful tablet is one whose form factor disappears when you're using it, a device with an invisible, yet immersive experience. We know the iPad does that, I expect the other two should too.
Price of the TouchPad is unknown. The Xoom is rumored to ridiculously cost $800 which would guarantee failure. Comparatively, an iPad at $500 is a steal.
The TouchPad and Xoom aren't available yet and don't have confirmed prices. If either are significantly more expensive than a $500 iPad, it becomes a lot harder to justify when the iPad is already such a great tablet. If they can manage a similar price, they both offer better hardware and more versatile software.
However. The iPad 2 is coming soon. If the iPad 2 improves on its specs, which is a given, that will change everything. Exciting times in tablet land! But, really, completely unknown. It'd be best to wait until the TouchPad and Xoom get priced and the iPad 2 is announced to make your final decision.