Had my 300 for a little over a month and was really enjoying it; I especially liked the added functionality that came with the keyboard/dock (SD Card reader, ridiculous battery life, USB support, ease of data entry).
But then I discovered the screen cracked on it one morning. It was fine when I put it down, but it was in the dock, and I think that was the problem.
A little research reveals that the plastic device that holds the tablet in the dock puts a great deal of pressure on the glass. Try moving the clip manually without the tablet in and you'll see what I'm talking about.
At any rate, I'm sending it in to the service center (at my expense) to see if they will replace it under warranty. I'm keeping my fingers crossed; this is clearly a product design issue.
In the meantime, be extremely cautious when your 300 is in the dock. Don't 'close' it like you would a laptop; just remove the tablet. You could be saving yourself some grief!