User experience is based on specs only to the point that you need to have your hardware spec'd highly enough to provide the user experience you want.
For example (and I am going to make these "specs" up), perhaps 1 GHz chip is too slow to provide a silky smooth user experience, but 1.25 GHz chip is powerful enough. Perhaps 128 MB of RAM isn't enough to run the OS smoothly but 512 MB is the minimum that it takes to work well.
Apple's approach is to put in the 1.25 GHz chip and the 512 MB RAM and call it a day. They have produced a tablet that provides a "silky smooth user experience", they have kept their costs down, and that's how they market it and sell it to the consumer.
Other tablet company's approach would be to sell it on the specs. The bullet points would read "1.25 GHz processor! 512 MB of RAM!" Which can be misleading because those numbers by themselves tell you nothing. Is tablet A with 1 gig of RAM better than tablet B with 512 MB of RAM? Can you unequivocally answer "yes" without also knowing what kind of OS kernel, what kind of apps, what kind of memory management is going on under the hood? Are we, for example, comparing an iOS tablet with a Windows 7 tablet?
Apple's tablet has 512 MB of RAM while some competitors might be offering 1 gig, 2 gigs even. By specs alone, Apple's offering looks terrible! By specs alone, Apple had better offer 1 gig, mininum, just to keep up with the competition. This of course would raise the iPad's price or reduce Apple's profit margins. And it is the "specs alone" people that argue in the forums that Apple's offering is so outdated, so obsolete, so behind the competition.
Yet people who actually try and use an iPad, myself included, don't even realize (or care) how much RAM is in the device. I just know that it works well, it's smooth, it's responsive, and it runs the apps I want. That's user experience. I've never once thought "Gosh, my iPad would be even better if it had twice the RAM!"
Now, of course, eventually someone's going to come up with some great apps that actually use a lot of RAM, and my iPad might struggle to keep up. That translates into "poor user experience" (sluggish performance) at which point I will say "man, my iPad is getting too slow to run the modern software. I'd better upgrade". There's your example, once again, of user experience driving the need for better specs. But it is not the other way around.
