For vector and illustration its certainly very useful. There are absolutely awesome apps out there. Photo editing is limited, your best bet for RAW processing is Affinity Photo, a great little app, but sadly its nowhere near desktop PS. Video is almost hopeless, only very basic editing can be done. The recent video apps are a joke, all of them, cant even be compared to premiere or davinci resolve. They were meant to cut little clips, shot on the phone for social media.
However i find the bottleneck to be something else: the total lack of file management on IOS. Until theres a new operating system, the ipad has no chance to be considered as laptop replacement.