Been carrying mine around in an external mesh on my laptop bag for ages without a problem. Usually goes in with the cover closed and face inward.

The screen itself is like any screen. Poke it hard enough and it breaks. Luckily for most people, it's fairly hard to do that since most accidents involve hitting the case before the screen (which lets the case absorb most of the impact).

As for the coffee table....depends. If you are worried about things like books and magazines getting piled on top, you would actually be pretty safe since the case would hold most everything away from the screen. But if you're worried about dropping smaller items on it (cans of soda, game controllers, very tiny frozen water buffalo, the hands of toddlers and drunken friends) then yes, it's dangerous for the reader.

If you find yourself REALLY paranoid about the loss of such a desirable object, do what we did here:

1) Slice open cover.
2) Insert thin aluminum sheet cut to a little smaller than the cover itself (we used titanium due to a scrap bin 6 feet from the office).
3) Reglue the cover and enjoy what is basically a bulletproof coat for your reader screen while closed. (NOTE: Do not use as an actual ballistic protection device. Do not use this modification if currently involved in a firefight. Void in parts of New Hampshire, Rhode Island and Terra.)