Hmm. I have to confess a bit of bias here. I bought an iPad on release day (not as part of the madding crowd, but I happened to be near an apple shop anyways, and I wasn't going to drive two hours to get back to it another time)
I've really enjoyed using the iPad over the last few years, and it's still going strong now, and I still enjoy using it (when I can, her who must be obeyed has acquired it). I've bought countless Android tablets in that time to try and replace it, and none of them have really been capable of making me sit up and go "Yes, I want to spend time with this tablet" - and it's not like I've bought only cheap ones - I've had a Galaxy Tab (it was OK), Viewsonics (for the price, fairly good), Motorolas (Please, not again) Acers (not bad, but I'd rather have their W500 than the A500), some cheap un-named thing off eBay, and ended up selling them on in fairly short order.
Hardware wise, they've all been OK. Software wise, Android has potential, but for me, not being able to use a proxy server is a real issue and one google don't seem to be addressing, but the two seem to have been thrown together at the last moment by people who haven't actually talked to each other at all during the development process, which has been disappointing.
My latest attempt at a non-Apple tablet is the BlackBerry playbook - I didn't buy it until V2 of the OS was out, and it is a lovely little tablet with a cracking screen, a good browser, understands proxy servers, and generally plays very nicely. If I had to gripe, I'd like a longer battery life, and I'd turn off some of the bezel gestures ASAP, but I can see myself using it in 12 months time, unlike the Android ones. If anything though, it's crippled by a lack of decent apps - although the ones that there are tend to work well, unlike Android Marketplace where there might be 15 apps which are cr*p to the one useable one...
So maybe someone did come up with a usable alternative, but no one noticed it amongst the hordes of dross on the market?