I got 50% on my fronts and 35% on the rear. MN legal limit is 50% for sedans all the way around, but "wagons" fall into the same category as Trucks / Vans / SUVs so the rear can go as dark as you want. The hatch is technically a sedan still but most cops I think consider it a wagon still. It's in the same category as the Vibe, Matrix, Versa, Fit, etc. and I see plenty of those cars with darker tints in the rear, so I'm risking the technicality of the law... I'll post pics later today - going to wash her first...
50% isn't that dark, but it's enough to make it worth doing IMO. I had Formula One Pinnacle (ceramic tint - doesn't interfere with GPS / AM / FM) put on for $329. It was a bit more expensive than other places, but the warranty, reputation / longetivity of the tinter, and the highest-quality-tint you can get justified the cost in my mind. The Mazda dealership wanted $500 to tint the car, though they just outsourced it to another place. The markup for going through them was at *least* $200. I said no thanks.
If you're curious what brand of tint to get - stay away from 3M. Solar Guard is the best you can get if you can't get the Formula One line. Formula One limits the number of installers in each state and they have to get certified and jump through a lot of hoops to be able to install the product. This is why you probably won't hear many tint shops talk about it nor even be able to compare it to the "best" Solar Guard tint. Find the installer nearest you that does install the Formula One and go check them out.