It's super easy and comfortable, actually. The only thing that might bother me a little is iPadOS, which has been a little buggy lately. Otherwise, 13 inches of screen and storage isn't an issue at all.
The screen is not small IMO. If it is for you, you can hook it up to an external display via USB-C to USB-C/HDMI or wirelessly via Airplay and basically turn it into a laptop/desktop with all the bells and whistles like external sound cards, keyboards, mice, external displays, MIDI instruments, microphones, HDDs/SSDs, etc.
I went for the 256 GB model which always has 100+GB of free storage because I always archive the finished projects onto either cloud or my own server, and delete them from my PC/iPad. Storage has never been an issue for me for as long as I can remember, but the iPads go up to 2 TB of internal memory.
I think that my only frustration with this thing is that it has the same hardware as the iMac/MacBook, and only because of the OS I can't install desktop programs on it. In your case, what part of a full-blown OS would you miss if you were to use an iPad to edit photos?