Yes, it did take a long time to install
A clean install on a 600Gb HDD, less than 10 minutes, including formatting (deleted old partition and re-created it).
So far, very impressed and would consider buying it when the RC edition times-out. I haven't found the XP emulation mode yet though.
As someone who wouldn't buy a new PC unless it had XP installed, Windows 7 has been a real eye-opener - so far.