The 303 worked pretty well for me. It didn't change the appearance or leave any residue on my fabric upholstery, and on rainy days I can see the water bead up right on the surface of the seats while the fabric stays dry.
What I didn't like was that the spray nozzle on the 303 bottle only shoots out in streams. I don't know if the nozzles are still like this. It made it difficult to cover a surface properly. I would use a spray bottle with a good misting pattern.
It's also expensive.
And yes, it does smell very chemically and take a long time to dry, but as far as I know, every other brand of fabric protectant is like this too.
