The clear UV resins work well, overall, but it depends on what you what to do with it.
I've tried the Loon wader and knot sense stuff as well as the Aqua seal wader patch and the Bug Bond brand. All work to coat the wing case of flashback flies. Two coats of Sally Hanson's HAN for small jobs like wing cases too, though.
For "epoxy" flies like surf candies and sand eels, the UV stuff works okay, but clear epoxy is cheaper. You may a drying motor to spin the epoxy flies.
I've never used it to coat poppers, I use epoxy and spin them with a motor, but plan to try the UV stuff out.
For both poppers and epoxy flies, a rotary vise to cure the UV resin should work very well.
One thing I've found really handy for the UV stuff is putting a small dab on the base to set tails or wings or legs on a fly. Hit it with the UV light and it freezes it in place. (It's cheating a little bit, but no one will know except you!)
Also, I use UV resin to coat nail knots and loops on fly line as well as making small repairs to lines with cuts or nicks.