Have been listing and buying items on my mini with 7.0.3 this weekend, not noticed any problems with the app. My iOS 7 was a clean install but incremental updates applied normally.
I'm with ya the main lags I see are of course during start up and when I hit the search bar or move from the home screen to any of the 3 options of buying selling or watching,but other than that mine goes smooth especially when listing.