Color Balance is the sensitivity of the film to red, green and blue. This is pretty important because it affects how the final print will look and how much nebulosity shows up in extended objects. Also stars themselves are quite colorful and a well-balanced film shows those colors to their best advantage. The final characteristic is reciprocity failure. This is the loss of efficiency of the film over the exposure time.
Some films maintain a slow loss of efficiency over the exposure times typical for astrophotography.
Other films loose efficiency so fast it would make your head spin. For some reason the faster films seem to loose efficiency at a far greater rate that the slower ones. While this is not a hard and fast rule, it does make a good rule of thumb. As an example, Fujicolor 1600 is a very fast film but after 10 seconds of exposure it slows considerably and after 1 minute it is gathering far fewer photons than some much slower films and this trend gets worse over time. Fujicolor Superia 400 is a much better choice if your exposure is going to be longer than 30 seconds or so.