Personally, I prefer a physical keyboard even on mobile phones. Even though I don't use the keyboard that much on the Kindle when I need it, it's there and IMO (and experience) faster than an onscreen keyboard. Aesthetically, the keyboard may give the Kindle a "clunky" appearance but IMO the keyboard gives it a functional appearance.
I own many different devices but I keep going back to my Kindle because for me it gives the best reading experience. I'm hooked on Whispernet, the social features are an interesting extra, and the new Pearl screen is far better than any other eInk screen I own. Everyone has different tastes and priorities and there's bound to be a suitable device for most.