I did the WRX brake upgrade yesterday. The learning curve on the first rotor is always the longest. The other rotor went pretty quickly and the brake pad change on the rear only took 10 minutes per side.
And for those of you who haven't done this before, get yourself a large C-clamp to push in those caliper pistons and an 8mm x 2" bolt to pop off the rusted on rotors.
Here are some pics between the old rotor and the new rotor. I can definitely tell a difference in stopping power between the two. No it's not like going up to a large Brembo or what not but it's darn nice for the money I spent.
As you can see, the new rotor is just a bit bigger and pushes the caliper closer to the outside of the rim.