The Batch processing feature in AP is good, but needs some attention. Here's some missing features I think the app would benefit from:
Ability to pause/resume batch and stack up multiple 'jobs' for processing, potentially with different settings, before starting the batch for all of them
Better CPU management - to avoid Windows lagging to unusable levels during a batch job (even with parallel disabled), or throttle the amount of CPU used
Option to remember last processing settings - and set new persistent defaults
Ability to save presets for processing settings (formats and their respective export settings, file names and so on)
Ability to jump to the persona and go into mode ready to create macros, straight from the Batch dialog
Feature to rewrite / rename / create new file names (either regular expression filename modification, or write new filenames based on a structure using inputted text and variables)
Ability to apply a RAW development from the Develop persona to multiple RAW files (at the moment, to batch develop RAWs I need to use Canon DPP4).
When opening CR2s / RAWs, the ability to preview them in the File Open dialog using Affinity Photo's RAW engine would be useful. At the moment, previewing them relies on having a CR2 plugin installed in Windows.
Apologies if any of this is already in the Photo roadmap.