I'll start with the most glaring omission. How do I take a USB or FireWire hard drive and connect it to the iPad? How do I connect an FAT-formatted SD card to the iPad and mount it as a normal drive? The latter must work now, because that's what I regularly use to transfer files. If the answer remains "You can't, but you can buy a laptop," that's not an answer. Where is the SD card slot? Where is the USB port? Where is the video-out? The problem with using adapters connected to the only port on the iPad, which is proprietary, is that it can only do one thing at a time. I need I/O ports, different ports for different tasks, and I'm being told that the iPad won't natively support normal file transfers.
Apple doesn't define what a tablet PC does. The buyer does, and I say that a tablet PC must have basic file transfer capabilities and a collection of normal I/O ports. It's pretty useless to me without those capabilities. There is no good reason why the iPad can't mount USB devices and SD memory cards as normal drives, and without cracking whatever Apple did to disable this functionality.
Another glaring problem has been the apparent restrictions surrounding iOS. Software that I want to run I'm being told will never be supported because of Apple's refusal to sufficiently open the iOS code to developers, and because of restrictions in its application store, to which the iPad is locked. I don't fully understand this problem, because I think that I should be able to run and distribute whatever software I want without Apple getting in the way, but the bottom line is that what I want will never be running on iOS. It will, however, run on other tablet operating systems, and that's what gets my attention.
The reason I started looking at a tablet PC was to replace the laptop in my bag. If I can't do that, I'm not going to buy a tablet PC. Oh, but I found that I could do that, once I started looking away from the iPad glare. This reminds me of another problem. Why does the iPad not use a better screen that isn't covered by a reflective surface? The thing looks like a mirror, and it's awful in the sunlight. I know there's something better, because I've seen screens that look great in direct sunlight. Why doesn't Apple implement this technology?
The competitors may be regarded by Apple zealots as mere annoyances, but they provide tools that do things better than the iPad. Apple may be pleasing the masses, whether they buy because of a herd mentality or because it has simply been the best tablet PC for consumers, but it isn't the best tablet PC for me. I was hoping that the iPad 3 would resolve at least some of these sticking points, but now I'm looking elsewhere for a tablet to meet my requirements.