I have a really great experience with my portable Hummingbird (sounds like some others maybe not). I turn off the the side view and just use the down view with auto res and the fast screen roll.
I get over 50 hours out of the 6 AA batteries, just need to change out once a month to six weeks.
I do find fish on mine, if there's something there it will pick it up: bottom contour, picks up weeds / vegetation, and even used out at Quabbin to find smallish in 20 feet of water with a drop shot.