Expect something like the Aerosoft A320. Not detailed to save on performance. Just a very rough model, primarily because this add-on is for people who like to simulate the operations of a pilot, not of passengers. What exactly do you mean by interior sounds? Everything that is heard in the cockpit is packaged. But don't expect flight attendant's announcements.
I recently installed fsx se and later bought the A320/A321 DLC. I have flown it for a couple weeks and decided to get another DLC (Feelthere ERJ 135). I have since removed the DLC because it was terrible but not completely as it is on my installation list. It also made the A320, when loaded into the game, go down to a frame a second (no matter with scenery minimal or maximum quality) and freeze. It also still plays the noise of the engines in idle and nothing happens. I also uninstalled and reinstalled both FSX and the Aerosoft DLC and it did not help. If any one knows what is going on, please let me know.
The following legs have been ticked off:
109.1 LGIR Heraklion to LGSR Santorini, and it's raining, for a change!
109.2 LGSR Santorini to LGSM Samos, still raining....
109.3 LGSM Samos to LGMK Mykonos
At least it's stopped raining on the Tarmac...