Cons: Takes a little longer for full effectiveness, hard to find
Even if I didn't seek out natural cleaning solutions, I would still use Seventh Generation's toilet bowl cleaner. My toilet bowls sparkle after being cleaned with the product and the subtle smell is very nice.
For years, I depended on bleach-based toilet cleaners and those awful bleach/blue tabs in the tank (which are so much more trouble than they're worth.) From the first time I used Seventh Generation's toilet bowl cleaner, I was sold.
The biggest draw is that the product uses naturally derived acids instead of bleach to get the job done. This not only prevents more toxic bleach from finding it's way into our waterways, but helps keep the house free of bleach fumes. I know that if I accidentally splash some on my skin or my clothes, there's nothing to worry about - I just rinse and go.
Application is fairly typical, there's a built-in flip-up nozzle that shoots a narrow stream of the liquid cleaner under the rim. From there, you allow it to to slowly run down the sides of the bowl and scrub as usual. The natural thickeners help keep the cleaner thick enough to coat the entire bowl. Once you flush, you'll see what a great job of cleaning it does. After a few weeks of using it, I found that the waterlines in all my toilets had disappeared.
The directions instruct you to allow a few minutes before scrubbing, though I find it best to allow a few hours before scrubbing. Though this seems like quite a delay, it's really no problem if you remember to squirt it into your toilets before you start your other cleaning chores. My only other complaint is that it's hard to find, I've only been able to buy it at Whole Foods (which isn't near me) or online.
