There's been so many posts on this very topic; just look through all the old ones. My opinion is, and it is just my opinion,that WFP is better than traditional, full stop.
Someone will no doubt disagree, and that's their right, but to my mind it's safer, quicker, does at least a good a job as traditional, probably better when done properly, allows greater access to akward/high windows, allows my business to secure work I'd not have been in a position to go for before I invested in it, looks more professional, the list goes on and on.
Downsides?
initial outlay, hoses catching on everything, having to fill the tank/ charge the battery over night ( though in all honesty it takes only five minutes to sort out each night ), higher running costs ( Much more than off set by the higher earning available ), and not a lot else.
If anyone tells you they can earn as much with a mop and squeegie as a WFP operater they're very mistaken; it's as simple as that.
If you've not done it yet invest in a WFP set up, using genuine poles, etc and you wont look back, I promise