I have the i5 256gb model and I use Lightroom and PhotoShop frequently on it with raw files from my d800
The screen maybe small but it's excellent , I found I actually preferred editing with Lightroom on it rather than my old dell 2407, its great using the pen and touchscreen. PhotoShop is also pretty good.
Its powerful enough for general editing and the battery lasts a reasonable amount of time unless you hammer it with intensive tasks.
I put a 64gb micro sd in also just for some extra storage capacity but I tend to upload everything onto a nas drive once I've removed the chaff
I still use my desktop too but I really do like this surface pro3