I've been using these for a few months now and I think they are a terrific tool for anybody who wants to improve their work from life. I am of course indebted to the indefatigable David Kassan for this suggestion (http://www.davidkassan.com/).
I know what you're thinking... this is just a tool to render the life out of things, and who needs all that detail? But hear me out:
1. These aren't just any binoculars, these are the Pentax 0.5m Papilo 6.5 x 21, 'extremely close focusing' 0.5m/1.6ft binos. In other words, you don't have to be standing too far away to use them, as you would with other binos. They are good for a situation where a model is on the other side of the room from you, for example, or where it's awkward to walk up and get a closer look at what you're doing.
2. You don't use them for designing a painting, or planning the concept, or squinting for shadows, or even necessarily for detail. You use them to establish accuracy of placement. I find them especially useful to help me with any spatial confusion I might have on an object. In other words, if I can't really see what is in front of something else, I might be tempted to treat the whole area as one unit. This is fine if that is what you want in your painting, but if you want to add detail, or sharpen an edge, etc. for any aesthetic purpose, it is nice to see what you're doing and make an informed decision. It's a decision making tool, basically.
3. The binos help you focus your mind on the area you're painting. This last point surprised me, frankly. I suppose it's a little like putting blinders on a horse - you're not distracted by the nonsense going on next to you, or what else might be rumbling around in your mind at the moment. You're focused on getting one particular area correct - that's it.
Drawbacks in using these include arm strain from holding them up to your eyes, and the sheer goofiness of how they look when you put them on top of your other glasses.