Hmmm, I'm wrapping up a replay of all three GoW games right now.
I bought and beat the first one not long after it came out years ago, but wasn't too impressed and eventually sold it.
About 9 months ago, I decided to give the franchise another shot, re-bought the original, and also picked up GoW II and CoO, both of which I had skipped. II was such a huge improvement. Despite having played through all three in a marathon last year, picking up the recent Collection for the PS3 sparked another play through (now with trophies). With I and CoO replays both behind me, I find myself almost done with my replay of II, and once again, I can't help but think that II is such a leap over I.
If III can be even half the leap over II that II was over I, it should be relatively good times!