I like how easily it integrates with my tool set, whether its Adobe Illustrator or Photoshop! It's just not quite as intuitive when using other 3rd party software such as Affinity Designer etc - but really this doesn't detract from any benefits we get out of sketchcop itself (which are numerous).
The UI could be more modernised for non web designers/developers. Try before buy would work well here too if all customers can use their own graphic assets which might save some time! We have been able create an entire website within 15 minutes without having used adobe illustraotr at ALL so far!. That saves us money upfront because our clients don;t need those expensive plugins they'd normally require otherwise.