Just recently I bought some cheap universal seat covers and tried spraying the NeverWet on those, I didn't want to worry about it staining my seats, and if I didn't like it I would just take the covers off.
It's been holding up pretty good, no staining on the black seat covers, and I'll take the function over the "frosty" coat.
I did a fairly light base coat though, reading the instructions that came with the spray it said a light base on fabrics still lets them be breathable. Breathable seats are important in the Florida summer.
I'd say they are at least 50% water proof. The seats still get damp after a rain, but they dry in just a couple hours. And I took the carpet out too of course, so the water rolls off the seats and eventually out the drain plugs.
Haven't tried the stereo or steering wheel, but I may have to do that. I got caught top down when a fast but heavy storm hit while I was sleeping in the morning. I've been having some airbag and horn issues after the steering wheel got a good dusting