First, even the "manual" version of garbage collection (the retain/release) pattern is pretty trivial with Objective-C (more so with the new property syntax). Once you know the rules it was pretty automatic and really didn't cause that many problems. It was more a problem with the "checklist" language comparisons.

The "property duplication syntax" (I assume you mean the declare versus synthesis) is there for flexibility and so you can do some pretty good customization to make your classes work better.

For OS X, Objective-C now has garbage collection that works pretty well.