Hi,
So this topic actually deserves an article alone. You see, as an artist you usually work with what looks correct and so far Blender has been a very artist-friendly tool. Values for materials and lights were mainly unitless and we used to work in rather shallow dynamic range (most even from 0.0 to 1.0)
Now, last few years have been “physically based rendering” years in CG industry. Blender moves in this direction too. Suddenly you have to think like a photographer and optics scientist 
It is a large leap for someone who just want to make things that look right.
PSA is attempt to bridge the gap, it is an ongoing experiment and sort of community assisted project (as you see here in comments)
So to answer to your questions:
yes and no.
yes it is more complicated because you will have to know actual light source properties like watts, temperature and luminous efficacy (instead of intensity and RGB color) to get the light shine correctly. You might need to use PBR materials too. And then you have to use correct camera exposure parameter and tone mapping because now your shade luminance can be a value of 100 and lit surface - 3000.
no - not problematic. If you go through the process few times, you will notice the increased render quality and reduced time spent on tweaking things. Stuff will just look right out of the box.