I saw the series just once, but I longed for each episode to come round. I have the book (which is good) but OHHHHH I would like to see the series again.
Expect atmosphere. Expect uncanny. Expect thrills. If you get the chance, take it. You'll be haunted by the memory! Don't expect fantastic effects, ray guns, funny aliens or obscenities. You don't need those to ice your spine. In fact, good stories, good acting, and good dialogue are far more important, and although it's been a few years now, I seem to remember that the Omega Factor has all those.
Why it isn't on DVD is a mystery worthy of the program itself. It's like Kolchak:Night Stalker and Australia's own "The Evil Touch". An absolute gem, but as with all gems, hard to find.
Channel 2 (in Australia) showed this series, so perhaps if you live in God's own country you might like to pester the ABC into a reshow.