this is the first time in 12 years of updating OSX that I've encountered an issue.
I always update my MBP first before my main iMac, and after downloading the update the installation froze completely, requiring a restart. I then downloaded and installed the combo update with no problem at all. I'm now updating my iMac, but with the combo update as well - don't want to risk another freeze especially on the machine that connects to all my important stuff.
Just one query with the combo update though, when I downloaded it, it was around 2.5GB. But the installation wizard said it would take up around 8.5GB of hard disc space.