well, depends. i've got my HP Touchpad because it was a firesale. i can also understand getting a Transformer Prime because that line's entire premise IS that your tablet can double as a laptop. it's also packing a quad-core (well, quin-core) which is pretty insane for the price you're getting. this one's actually fairly competitive and overall the extra portability does it well.
most others though yeah, not much purpose to 'em. some cheaper ones sure. but portability's the main selling point. they're the niche between phones and laptops (or netbooks if you wanna go that route) right now. eventually phones will take over 'em again, ditto for laptops.
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The King Wang.
Listen up Urinal Cake. I already have something that tells me if I'm too drunk when I pee on it: My friends. - Colbert.