I know the guys that do use them seem to really like them. I've heard the Lowrance Ice conversion kit for their color sonar/GPs units is much better then the Cabelas's kit, they sell for around $200 which is a little spendy. You may be able to rig something up a little cheaper.
If you've got short, stubby fingers and wear reading glasses, any relaxation you would normally derive from fly fishing is completely eliminated when you try to tie on a fly. ~ Jack Ohman, Fear of Fly Fishing, 1988