I did this for the first time last year and it's the first date in the diary each year now. Very well organised event with many of the legends of fell running taking part e.g. Joss Naylor still competes each year. I agree it probably is the navigation which probably puts people off.
Despite knowing the Lakes reasonably well the two courses I've done have taken me off the main paths to places I've never seen before and probably would never discover otherwise. The waterfall at check point 3 last year and the tarn below Great End at check point 4 this year stand out in particular.
The classic course is apparently more demanding than a few years ago and I just managed to get round in time this year. It's probably similar to Wasdale in terms of distance and height. This might put people off but there are the medium and short course options.