Same here, except it took about 10min to download, 20 min to install. No problems at all so far, except that it is no longer an option to uninstall IE7, should you want to.
For those that want to retain the ability, uninstall IE7 before installing SP3.
I saved SP3 to a folder, installed from there, so if I ever have to reinstall Windows, I can just slipstream the service pack on to it, or at least install it following the reinstall.