I'm pretty impressed with the build quality.
My several unscheduled drop tests off dashboards and tables have not damaged the 810.
My only "niggle" is the SD card slot & cover, but I don't use that much anymore.

The kickstand seems solid enough but the detents could be firmer.

The battery cover is confusing even though I know how it has to go back in.

They need to move the USB connector so it isn't covered up by the kickstand (they could add charging and move the charge connector below the kickstand since I usually charge it that way, but use host-mode adapters and USB keydrives or other things often).

My major hardware annoyances are:

Kickstand covers USB (already noted)

Ambient light sensor is where my left thumb goes when I'm holding it.

Wifi antenna is where my right hand covers or interferes with it.

The gap between the touchscreen and case is enough for stuff to get stuck.

A few more external keys (like the joypad or even user definable) would be welcome. And a mute switch or button!

Overall build quality of the 810 seems to be ok for me,
although my former 770 felt much more solid.

The dpad is too near to the sliding top case half.
Pressing the 'up' area is a pain, as you have to use your finger nail
instead of your finger tip. This is a design flaw IMHO.

The keyboard's tactile feedback is very different on different keys,
and the keybord backlight is unequal across the keyboard,
some letter are much better readable than others.

Just take a look at an OQO 02 keyboard to see and feel what quality means!

However given the size of the 810 it's nice to have a keyboard at all;-)

Overall I really like the design and construction of the N810. The only thing that really strikes me as being odd is that the two buttons on the face aren't backlit. They look like they should be with their cut metal symbols and white underneath. It doesn't take long to "memorize" them, but unlike the n800 there isn't much texture there to help you locate the one your after quickly in the dark. Certainly not a deal breaker though

My battery does rattle if i shake it, i might try the fix of putting some tape there. I did the same thing on my 770.

I also noticed that the gap between the sliding screen and the base is a bit more wide on the right side than the left. I can push it together on the bottom, but on the top there is a little metal piece in the way (the anchor?). It still slides smoothly, so I'm guessing that's just how it was designed. I can also see a little IC when I slide the screen up all the way and look at the back.

I like the brushed metal look and the screen doesn't have that rainbow fuzz effect that the 770 had. Sometimes it seems the left speaker is louder than the right, but maybe that's because my hand reflects the sound on the left side. I think the microphone should have been placed on the front of the unit, not on the bottom, but I guess it's better protected that way, and it seems to be pretty good at picking up sound. The webcam is one of the worst I have ever seen, but it works. The ambient light sensor should have been put in the top center.

I have no problems with the d-pad other than "why didnt they put it on the front" or just give me an enter key, or some kind of key which brings up the on-screen keyboard. I have to tap multiple times before it finally brings up the on-screen keyboard...

For the people with stuck batteries: screwdrivers and Li-ion batteries are probably not the best combo, though you won't do any harm if you're careful.
But my technique (N800, tight battery) is to remove the back cover, hold the N800 by the end with the power jack, and thwap it against a cupped hand. The battery comes right out and lands in my hand.

the n810 is tougher than i thought ... ive dropped it multiple times and still no damage.... though it doesnt feel very sturdy like the 770 or the 800...