Windows has taught me (through the error that Vista managed to generate when i was using it) that the 'restart' button is a useful tool.
More as a comment on Windows 7 than a complaint, the main issue I have encountered in a meagre 4 days of use is that the computer always manages to discover that some program is still open when in the process of shutting down.
The most recent case:
Upon hitting restart, I am removed to a darkened screen telling me that a program is still running. This time, instead of it being Firefox or Open Office, it was explorer (as in explorer.exe)
Windows chose to tell me that I needed to force a shutdown as explorer.exe was busy "playing the log-off sound"
I could not cancel, however I could access that ctrl+alt+del page, but could go nowhere from there. and then it froze.
Yesterday it also froze 20 updates into installation of 23-updates. Complete lack of response from the computer - issue was resolved when restart was forced and it installed the updates later with no problems.