Agreed, the appendix is a good place to start, and to really use it one must go through it and pull from each version the sections that it discusses and see how the change came about. The difficulty to be overcome is that there is not always a one-to-one correspondence. However, difficulty is what makes the learning memorable.
The foreward also provides insight. Not exciting, but useful.
'94 clarifies a few things and adds at least as many new gaps as filled.
How beneficial it is depends on how much the previous standard was used and how properly.