The 7316 is a direct sub for the 12AU7, ECC82 etc, pre amp tube. It is selected for low noise and high reliability and has been made with more than one architecture. The were intended for fine instrument and computer use. They are, if real, my strongest favorite sub for the 12AU7. You are more likely to get a real one always Heerlen Amperex with Ct# date code for late 50s and early 60s with a computer company logo like Hewlett Packard.
So you ask what's the tube sound like? It is a tube that is capable of crystalline highs without being piercing and creates an almost surreal technicolor three dimension soundstage, pure mids and again very dramatic frequency range digging into the bass- and getting out a clean non muddy bass. Beyond that I just like the way they sound.
If you get a 7316 that sounds like crap it either isn't a true 7316 or is well past it's prime, keep hunting. Unfortunately there are some dishonest or ignorant sellers who are giving their better 12AU7s the 7316 name. Make sure there is the right triangle acid etch indicating Heerlen Holland. That alone separates much wheat from chaff. If all else falls write me privately.