It's just usable as a monitor replacement, but it would be a big stretch to say it's "better". If you have even a cheap a monitor available you'd nearly always be better off actually using it. The scenario where it's better are going to be specific use cases like:

- it's helpful to have it be gigantic - bigger than a real monitor could ever be

- you have a real need for more monitors than would be practical to buy or position in your work environment

- you will be highly mobile and moving around so much that it's going to be better to take a headset with you than try to get monitors everwhere

- you really would like to collaborate with someone else who also has a Quest Pro, in which case you can work together without being physically together

- you highly benefit from / enjoy working in alternative environments (eg: being highly focused, free of distractions, relaxed, surrounded by beatiful scenery etc)

I actually find the latter point is the biggest reason I do it. Even when I'm surrounded by distractions I can go into a completely calm virtual environment and get a crap load of work done.