I was using World's Best for a while but Bootsie wasn't using the box regularly. Often she would hang around the box and sniff at it, then start meowing and run off. She would hold it for 24 hours and then pee a lot in the corner of the box and then get out real fast without covering because the box just offended her that much (if she went in the box at all, sometimes she would just go next to it). But it was better than some litters which she just won't touch.
Now we're trying the Arm and Hammer flushable variety. She seems to like it although she still isn't covering up her pee. I think it is okay and the smell of it doesn't seem to bother either of us. But, it is somewhat dusty and doesn't clump quite as well as I'd like.. but if she uses it regularly without issue then it is definitely worth it.