Lets just take a quick look at mobile OS and where they stand. You have iOS, Android, BlackBerry OS, Windows Phone 7 (I don't think it's on tablets yet, but it's coming) and finally WebOS.
Out of the 5, the absolute least support is for WebOS even though it beat Windows Phone 7 to the market by several years.
Simply by the virtue of it using WebOS it is inferior to all the other offerings on the market. It was hard to adjust to their gestures, but I think PlayBook did a decent job with user experience. I've only had a chance to try the WebOS briefly, but I found most of my experience with it to be rather painful.
With that being said, iPad is not the greatest thing out there. I personally think that the Galaxy Tab 10.1 makes for a better tablet computer. It's just as quick, has bigger screen and provides a better experience. I find with a tablet screen just having apps is a giant waste of space. I love seeing the android dashboard screens on a tablet sized screen. You can see your emails, weather and calendar all in one screen without having to open a single app. And it's got the second highest developer support out of all the other operating systems. Now if apple increases iPad screen resolution it will become hands down the best tablet. Most are just now starting to catch up so a move like that will put them back ahead by at least a full year. Once you've used the "Retina Display" no other portable device looks quiet the same.