I can't say much about the iPad, but I bought a used iPhone 3G a few months ago and really hated it, mostly because of the horrendous performance under iOS 4, because the 3G has an ARM v6 processor, whereas iOS is optimized for ARM v7 processors of 3GS and newer vintage. So I sold the 3G and bought a 3GS for a few bucks more, and I still hate it. It's slow, if not as slow, but my friend's Samsung Galaxy S (I'm stuck on T-Mobile, and that's pretty much the only smartphone they have aside from the G2 which can't be rooted and I will never buy) completely stomps my 3GS's snappiness. Also, I agree that iOS really isn't all its cracked up to be. The youtube app is whatever, its incredibly slow on my iPhone, but other wise the UI isn't too bad. I also don't care for Flash, its so slow and poorly implemented that I'd rather not have it on my mobile devices. But HTML 5 isn't much better. Sigh.
The multitasking in iOS was fairly satisfactory to myself, simply because a smartphone doesn't have the screen real estate for multiple windows. If I were running iOS on something with a 7" or larger screen, I would also be unhappy that it takes to so long to change from one application to another.
As for making the post, there's nothing wrong with posting your bad experience with a device, even when its one of big bad apple's devices. In fact, by even considering not doing it you're letting apple bully you around. Don't. Also, jailbreaking my iPhone made a huge positive impact on my experience with it, now that I actually own my own device. I hope you didi that?
I think in the end its just that you're not the target crowd for the iPad. You didn't just sit there and take in Apple's magic and be happy. Those people are simply not the people the iPad is targeted at.