If you look at the original review videos (or even the keynote), you may notice that the first iPhone lags quite a bit. Of course, it's not Objective-C that causes it, but rather the limited hardware of the time.
Their failure was due to management failures, stupid decisions like the "burning platforms" memo, or introducing new WP versions without backwards compatibility.
Nothing to do with the greatness of iOS that has created revisionists of the mobile computing platforms history.
