I got my N900 15 days ago. Since then I have experienced only 2 of the problems being reported through the forums:

1) Occasional power-offs (only 2 or 3 of them).
2) Bad front camera image quality (not a problem at all as no official application is currently using it).

So I can consider myself a very lucky person because of:
1) No reboots.
2) My battery lasts for long indeed when using 3G or wifi
3) Excellent camera quality. My friends are really amazed about the images I'm taking with a mobile phone.
4) No problems at all with the quality of the usb port

In resume, I can't seriously believe that I'm a so lucky person, so I must suppose that something has been improved in the production procedure as for the last batches and the units being delivered are of higher quality.

I'm very happy of having bouth my N900.