I agree, Objective C was a nice little language. In the mid-90s I worked on one of the few (only?) non-NeXT Objective C projects, the Swarm Simulation System. We chose ObjC over C++ because it was simpler and more dynamic. At that time the GNUstep project was pretty new and most of the good stuff was in the GNU ObjC compiler and small runtime. It worked pretty well, particularly the very clever tclobjc binding that made it easy to script Objective C programs.

I've never used Apple's modern ObjC but from the code samples I've seen it got pretty complicated.