I do have a Mini with Snow Leopard, and my iPad kills it for casual web browsing, which is 90% of what I use them for. There's no way you've tweaked your Mini in such a way that it competes with the iPad for instantaneous use. What about standing use (at a bank, waiting in line at an airport) or for sharing content, or battery life (which is better under Windows 7 than on Snow Leopard on the Mini). I've caught myself instinctively trying to touch links on the Mini screen but never missed the hardware keyboard for entering URLs or Google searches on the iPad.
It sounds like you've only use a Mini and not an iPad...I cannot fathom how browsing Facebook, or MacRumors, or CNN, or YouTube would be more appealing to anyone on a device with a form factor like the Dell Mini's versus the iPad's.
As an aside, MyDellMini.com is good for OS X support on that device, but I recommend InsanelyMac.com for general OSX86 help and discussion.
I haven't used an iPad, but I have used an iPhone, so I imagine it's similar on a larger, more comfortable scale.
I agree that the touch navigation is very comfortable to use, but I guess it depends on what you're doing with it. For me, I can't imagine sitting on the couch or the bed, and balancing the iPad somehow. I don't like the idea of always having to support the device with one hand (or my legs I guess) and touching with the other. With a clamshell design, I can rest it on my lap, or a desk and always have the screen facing me at whatever angle comfortably. Also, as I do a lot of typing, I like using a real keyboard, with tactile response. While, again, I haven't used an iPad, I imagine typing a lot on the virtual keyboard would hurt my wrists after a while, as there's no way that can be ergonomic. Now, if you're standing in line somewhere, I'd agree that the slate form is better suited, but I don't find myself standing in line often.
As for the speed, to each his own - I only have my own experiences to go by. The dell wakes from sleep in 1 second and is ready to launch applications or continue use. Safari loads in another second, and any bookmark in the toolbar loads as fast as my connection allows. I really couldn't imagine myself needing it to go any faster.