The Premier systems are really quite out of date. They are analog as opposed to digital. They require 3-pair cabling and line cords. They can be difficult to program. It requires extra hardware to add on a voice mail (Tip/Ring cards). It is not caller ID capable.
On the plus side, the telephones themselves are workhorses and are built to last.
The other plus, which is why you are looking at it, I assume, is that there are a lot of used or refurbished parts out there for a very low cost.
Also, one really annoying thing is that all of the phones were made to use one of two different handsets (electret (E1) or dynamic). If the original housing has been changed, or if the stickers on the bottom of the phone are missing, it is impossible to tell which phone requires which handset without simply trying both types of handset.

[This message has been edited by paul144 (edited October 07, 2004).]