Even with the slowness of the new app store, the somewhat clunky horizontal view design, the lack of various options that used to be there (gifting, sorting reviews, etc.), the fact that new updates aren't checked for simply whenever you visit the update tab in the app--as used to be the case all the time until this latest update to the app store--is rather annoying.
It's nice that it seems the app will check for and notify you of updates somewhat more regularly and/or reliably on its own, but (short of having a considerable amount of time pass since the last update check) not being able to manually check for them without having to quit the app from the app switcher tray or by force quitting it each time is a step backwards, especially since this functionality has previously been there for quite a while now.