I think at the moment the only real advantage the iPad has is it large inventory of apps, otherwise I think something like the HP tablet that is coming out soon looks better.
The vast advantage which Apple has over all its competition is its brand strength. That means when people think of Apple, they associate the brand and logo with stuff which is cool, sleek, minimalist metallic modern-looking (no plasticy-components) and above all -
fun and easy to use. (Remember the Mac-vs-Windows ads from not too long ago?)
On the other hand, fanboys who continually assert the technical superiority of their favourite Android/WebOS/etc device over iPad only reinforces the general perception, rightly or wrongly, that "Apple is for cool people; Android is for nerds", because many of the issues they complain about from Flash to RAM to operating systems about are completely non-issues for the average Apple consumer. (15 million of them have voted with their wallets, which I think has surpassed even Apple's expectations.)