I'll put in my 2 cents only about those points I can speak of...
On-screen keyboard is unusable
Allow me, this is a matter of personal preferences and habit... Of course I can't compare it to a real keyboard, but after the first couple days swype turned out to be (for me at least) as fast as a resistive onscreen keyboard (both with stylus or fingers, according to the keys size).
Mandating Capacitive touchscreen so any on-screen keyboard is too inaccurate to be any use
Only at first for me... I just had to realize and get used to the fact that before, on the resistive touchscreen, I used the edge of my finger or my fingernail to press a key, on the capacitive one I just needed to "aim" with the center of my finger instead of the edge... took me, say, 10 minutes to get used to it.
Must be online for OS not to crash
100% don't agree.... plenty of ways to keep it offline, it's even a system option without using any third party app... And I've got
no crashes at all other then the ones clearly caused by myself while experimenting something too "geeky", but those are not to be counted of course.
Patchy integration of Google services
Can't comment on this as the only one I need is gmail which is working flawlessly
No spell checking
Now, I admit I'm not 100% sure, but I think I saw that somewhere
Appalling CPU scheduling and memory management
Kinda agree on the memory part (samsung related though, not google)
Appalling integration of the IP stack and DNS lookup into Java services
Can't comment as it's not really my field of expertise
Unable to remove or hide system apps and bloatware
I don't really agree on this... for example, on windows mobile the only way to get rid of that stuff was flashing a whole new firmware.... on android you can do it with a simple root access, I myself got rid of some useless crap put there by samsung italy, and I'm still with the official italian rom, just rooted.
Android Market randomly not downloading apps
Had that happen a few times, agreed. Usually retrying a couple times solved it, but it's kinda annoying nonetheless.
Constant media scanning blocking access to user memory
I find that annoying only at boot, when it takes a while to complete the scanning. Once booted I don't really notice it much.
Email client crashes and hangs with abysmally slow performance
Can't comment: I only use the gmail client and it's working more than fine, but I guess you're referring to the other mail client.
Location embedding in photographs without an option of disabling
Didn't look for a setting in the camera app, but if you turn GPS off I don't see how it could embed an unknown location

100% battery notification cannot be disabled
Not really a problem for me, but I agree it could be annoying for someone
Swype is evil because:
Only offer updates via Samsung, not incrementally and independently
Cannot add/remove languages
... or you can opt for the "geeky", manual solution, find the version you need and put it on manually

Cannot disable auto learning feature
Never thought of that, can't comment.
I simply won't purchase a Google or Samsung product after the Galaxy S. Struggling on with 3rd party apps that mitigate some of the above issues is not the hallmark of a quality product, or a professional development environment. Shame on Google, shame on Samsung.
Well, out of all the smartphone I've had so far (all of them with WinMo before this one) I've yet to find one which did not need struggling with tweaks, unofficial optimizations, 3rd party apps just to make it work better.... my thought is: there's no perfect device, only better user-end optimizations (and I kinda like it, that's a fun part for me)
