I used Photoshop and Illustrator for years and years (going back to 1990's) and switched to Affinity about 2 years ago. There's a lot of little details that are different--say, when you grab a resize handle, does aspect ratio stay locked or do you have to hold down shift?--but I found that it wasn't tough to retrain. Most things are where you'd expect. It's certainly not like Gimp or Inkscape, where absolutely everything is different and it feels impossible to get anything done.