Their sound got a little "harder" with the emergence of amp technology. Brian did write differently than Bon...he is less concerned with plays-on-words and making sexual innuendo, which was one of Bon's specialties. Bon could turn making a bologna sandwich into a sexual remark, God love him for it. Also, AC/DC began to rely more on Malcolm's rhythm in the mid 80s which gave them a bottom-heavy sound. Malcolm is way underrated in my opinion...always was. Bon was a born rock star, one of the few people that truly never would have survived without a spotlight. I figure maybe 20 of those people ever lived, and Bon Scott is among them.
AC/DC will forever be in my top three to five bands ever. They were exactly what they looked like...a bunch of toughs who made no pretense to be anything else. They remained steadfast when every one around them started selling out their look or their sound for success in the 80s rock explosion. AC/DC kept true to their roots, and never really compromised that much. I guess that's why most people who only like one or two hard rock groups like AC/DC. Ya just gotta love 'em. Three chords, no waiting.