In Australia, this was screened all in one night (in Feb 2005) beginning at 7:30pm and ending at 11:30pm, four hours!
Independence Day (1996) did the CGI filmed city destroyed-thing and since then, all other disaster films (like this one) must be compared to ID4. No one will ever do it as good as ID4 so forget about even trying. But Category 6 has HUMAN things to watch, instead of the effects. So this makes it okay.
Brian Dennehy holds the show together with his fine acting, he plays an old man who gives a young female worker a go when others in the office don't. That might sound simple but such things hold my attention more than the crap FX seen in this show (The Towering Inferno-type seen of the chopper landing on the office building is painful!). The sub-plot involving the two women stuck in the lift is well performed and scripted. The sub-plot in the bank is also well done.
All in all, Category 6 is not too bad at all. However, if you look back at 1970s television disaster movies such as Irwin Allen's Flood (1976) or Irwin Allen's The Adventures Of The Queen (1975), you can see that something is sadly missing from these modern TV takes on the disaster genre...music.
Richard LaSalle scored those 1970s productions and his music brought life to any scene, even to a simple scene of a chopper taking off! It all comes down to a thing called film showmanship...which is partly missing from Category Six.