I have L/XL hands (can grip a basketball) and I have average sized pockets. So a 5" device is pocketable for me, heard of the Dell Streak?
A 5" device with thick bezel ... more like a 6.3" device yet people bought it and it was pocketable. I'm just saying everyone is different and rather than limit yourself to 3.9 inches, you can grab something tailored to you, but you go right ahead and enjoy your skinnys

Many people bought the N900 for the qwerty keypad. There are "next-gen" Android devices like the N900 --have a keypad. With the N9 you don't get this. And if you are contempt with an onscreen keyboard, then you must think about the slab Android devices, and the iPhone too.
Why do I mention the iPhone (its taboo)?
At least an iPhone 3GS was a very good phone for its time, as with the iPhone 4, and so too for the upcoming iPhone. Apple makes sure its devices are one of the best for an entire year, and after one year they are still great devices, its called company support. You WILL NOT GET THIS WITH THE N9!!!

The Confusing part of the UX is the left and right bezel swiping. There's bound to be applications (eg Fruit Ninja) that will require some sort of swiping in the same direction, and yes this will get in the way. This isn't news, WebOS has this trouble too, and soon even the PlayBook.

Its not about if 64GB is enough, its about simplicity.
I rather have a 32GB device and expandable with 32GB microSD. Then I can put my most used content on the device, and pop in the card when its necessary. Eg/ long trips just put in one with your emulators... or put in a fresh one to record video/photos too. There so small and I can keep them in a compartment in my wallet. It keeps one more device away (your PC), makes it simple, solves issues that many people experience.

Same thing goes for removable batteries. I rather have a fully charged backup with me, than a case that acts as an extended battery.

The 1GB of RAM is a very good feature. It allows the software some breathing space, too bad that really (really) powerful applications aren't sped up by extra ram, the A8 may bog it down (don't you know all apps will be running in the background?).
And it is FACT the Cortex A8 is outdated. Yes its all anybody needs, right now, but it is not future-proof. They will get outdated along with the ARM11's once Applications mature to provide more features/more performance etc etc.

Would you be happy if theres a dozen android devices that do something your phone cannot and you really want it, and what if you found out the older (Tegra2, TI44, Exynos) devices support said feature, and your device is only a year old!

But who cares as long as theres plenty of software modifications on the way to iron out bugs and make things run as effecient as they can, right? wrong!
NOKIA killed MeeGo, and Intel has slowed MeeGo's development (due to Windows 8?), and no other OEM has released statements to support it. Its a dying OS which hasn't been born yet. Something that frustrates me everytime I visit here.