I have Navionics and I can tell you that it would be worth the money if it only gave detailed info for one of the lakes that I fish. It is priceless if you want to fish drops, breaklines and channels that aren't visible to the naked eye. It cuts out a lot of guess work.
C.J.
Amen to that. That big blob of blue on Lake Conway dont do me much good. Works good as a GPS for marking stuff on the lake though.