Label me a Oxi-Clean fanboy!
I've seen out get blood out of a off white seatshirt that had been stained for many many hours. We did soak the sweater for a couple hours though.
But.. what really hooked me was when my roommates and I (3 college guys - you imagine how dirty the bathrooms and kitchen were) moved out of our apartment. Nothing I tried before could clean the stove top easily (previously I'd be there with a scouring pad for hours - Comet, 409, whatever). With Oxi-Clean, it came off relatively easy. Worked for the oven as well. Shower, toilets.. all cleaned using Oxi-Clean. If it wasn't for Oxi-Clean, we would not have gotten much of our deposit back. Those are the things I would use Oxi-Clean on as I feel it is most effective for those. It can do carpets but I think other things are easier and maybe more effective (Spot Shot, Folex).
One thing should be noted (for those that have never seen it) is that it comes as a powder and it works because (I think) of the release of gas when mixed with water (similar to how many carpet cleaners work). So this isn't an "instant" cleaner like bleach. Not really a wipe on/wipe off thing... more of a scrub on/soak/scrub off thing from my experience. Requires a little bit more elbow grease but gets out the things that others can't with the same amount of elbow grease.
Two thumbs up.
Oh yeah. My one con: smells kinda funny when used in high quantities, probably from whatever gas is released. I don't think there are any warnings about it being poisonous or dangerous, and I've not suffered ill effects, but it definitely isn't perfumed.