If the party was indoors then TTL-BF was not going to be much help.
TTL-BL, "Balance Light" attempts to balance the flash with the ambient light. This is particularly beneficial outdoors, where the ambient light is particularly bright. -BL achieves this by altering the ambient exposure to better mesh with the flash output. Some photographers like what it does and others prefer to control the situation themselves via TTL and exposure and flash compensation or by total manual flash and exposure control.
Indoor flash frequently presents a different problem. With comparatively much lower ambient light (no sun), the flash is dominant. Beyond the subject distance, the background rapidly falls to black. TTL-BL, when it sees the big discrepancy between the flash and ambient exposure, significantly lightening the ambient exposure and making everything look somewhat weird. When indoors, I recommend that you stick to straight TTL.