This is a surprise for us. For a long time, we have been thinking that Android apps crash lot more than iOS apps. Well, the recent research by Crittercism revealed that iOS apps now crash more than Android's and from the above piechart, it's pretty obvious why this is happening. I wish that this study was done with latest versions of iOS and Android taken out of equation. Then again the combined amount of crashes on iOS 4.2.10, 5.0, 4.1, 5.0.1, 4.3.5, 4.3.3 account for 70% of total app crashes (iOS and Android combined).
The above two charges confirm the general idea that the latest versions causes most amount of app crashes.
Crittercism analyzed a total of more than 214 million app launches from November and December 2011 from apps that use its service. For full report, read this Forbes article.