Problems:<p>- Lots of extra retains&#x2F;releases can cause significant and unpredictable performance degradation, and even crashes:  <a href="http:&#x2F;&#x2F;blog.metaobject.com&#x2F;2014&#x2F;06&#x2F;compiler-writers-gone-wild-arc-madness.html" rel="nofollow">http:&#x2F;&#x2F;blog.metaobject.com&#x2F;2014&#x2F;06&#x2F;compiler-writers-gone-wil...</a><p>- The language went from fun dynamic, optionally statically typed to strict static typing that restricts exploratory programming:  <a href="http:&#x2F;&#x2F;blog.metaobject.com&#x2F;2014&#x2F;03&#x2F;cargo-cult-typing-or-objective-c.html" rel="nofollow">http:&#x2F;&#x2F;blog.metaobject.com&#x2F;2014&#x2F;03&#x2F;cargo-cult-typing-or-obje...</a> <a href="http:&#x2F;&#x2F;blog.metaobject.com&#x2F;2014&#x2F;05&#x2F;the-spidy-subset-or-avoiding-copeland.html" rel="nofollow">http:&#x2F;&#x2F;blog.metaobject.com&#x2F;2014&#x2F;05&#x2F;the-spidy-subset-or-avoid...</a><p>- People no longer write class-side convenience initialisers :-((<p>- The benefits are mostly marginal, and the non-marginal benefits are needlessly bundled with ARC<p>- The C interaction model of the Objective-C hybrid language was made much more complex, somewhat defeating the purpose of a hybrid language<p>That&#x27;s off the top of my head.