My Wife had her Interview on June 1st. The overall process was smooth, but to get to and from the bus area to Embassy is the test of patience.
The Interview letter would say 7 am or 7.30 am interview, but it does not matter as long as you are the bus area around 6 to 6.30, but usually they do not give out tickets before 6.45am.
Police Certificate is not required for processing at Islamabad even if it says on your interview letter just ignore it ( they just have a general format for interview letter they just copy and paste) - Take wedding photographs and any other vacation pictures.
Once you are inside the Embassy the process is pretty simple as 1, 2 and 3.
Step 1 - Fingers Prints
Step 2 - Document collection originals ( Birth Certificate, Nikkah Nama Urdu And English translation and Nadra Marriage Certificate )
Step 3 - Interview - Prepare questions like how do you guys know each other? how did you get married? where does your spouse works? when and how your spouse got to United States? how do you guys communicate?