It sounds like most of these complaints are about mobile Safari and not specific to Sencha's libraries or PhoneGap.
"The title may present a slightly unfair impression. Not all of these issues have anything to do directly with the PhoneGap or Sencha Touch codebase, but are simply limitations of browsers, web-views and performance of mobile devices, though Sencha Touch / Phonegap framework does inherit those problems (and go to some lengths to work round the issues)"
But there are defects and issues in both PhoneGap and Sencha Touch that I mention. But I also recognise that they are both doing a good job on balance to further the cause.