Well I suppose being qualified as an Optician, I should chime in.
Progressives, Varifocal's or PAL's etc have their place (I wear them myself)....however there are lots of variables as to why a progressive lens might not work.
1. Obviously if the lens hasnt been set up correctly on your face, then your eyes will never really be looking through the correct part of the lens. These lenses are set up at your pupil centre at your long distance prescription. The power of the lens increases as the prescription converges to shorten up your focal length for near at the bottom of the lens. If the measurements are incorrect and/or they are sitting in the wrong place they will never be right and your brain will struggle to work binocularly etc.
2. New digital/Freeform technology works on 'as worn' measurements. The lens is designed and calculated to 'work back' on where your eye rotates. So if you sit your progressives on the end of your nose then you will never have good vision.
3. There are ALL SORTS of lens designs and technology, and some are more task specific if required. There are a lot of old, and poor designs out there in the market. At the very least you want to ask for new Freeform technology if you are considering getting some new lenses. Not all progressives are the same as you can start to see. Lots of companies design lenses, but few are good at actually producing good algorithms to correct vision nicely. My recommendation would be to ask your Optometrist/Optician the brand of lens you are getting. Stick with the brands like Nikon, Hoya, Varilux, Zeiss etc. These guys invest heavily into R&D (I know as I was trained by some R&D guys and spent time in Japan at an R&D lab).
I dont want to bore ya'll too much so I will stop there. But remember that Progressives are a 'Jack of all trades' and even I have a set at my model desk for close work only. One trick an old lens guy told me once was he sticks a pair of ready readers over the front of his progs near the end of his nose. His good lenses correct astigmatism etc, but because the progs have a smaller near part at the bottom, the RR boosts his workspace up....I tried it (it looks silly but it worked well)but I never said that LOL!
I will say that Progressives are terrible for when I am working on my plane!!! Trying to look up the top of my lens (because I cant move my head back 180 deg) at something close is a nightmare... Hence, I took them off, put my near glasses on, did the job. When I stepped back to admire my work I stood on my frame and snapped the arm off GAH!!!
Good technology, set up well and you will never look back! But never say never, in my experience some people just cant wear them, but they are few and are between.